Tonicization
Tonicization is a really brief modulation of keys, where you just borrow a few notes from another key. The key that you are borrowing notes from is usually called the secondary key, and the tonic of the secondary key is called the temporary tonic.
For example, in a piece of music in the key of C major, the tonicization of the key of G major would involve the use of chords and progressions that are characteristic of G major, such as the use of the G major chord, or the progression I-V-vi-IV, before resolving back to the C major chord.
The best way to identify tonicizations is to look for accidentals from closely related keys in a passage. This is especially true if you notice an accidental (that is not the leading tone in minor) resolving upward by step. This is called a leading tone relationship, and it is likely that this note is resolving to a temporary tonic note.
Now that you know the tonic of the secondary key, you can figure out which chord led into the temporary tonic. Most likely, this chord will have a dominant function, so it will either be a V chord or a vii chord in the secondary key.
You can only tonicize major or minor triads–not diminished or augmented triads. That means that in a major key, vii° cannot be tonicized, and in a minor key, ii° cannot be tonicized. In written music, it is easy to identify tonicization when there are accidentals.
It is most common to tonicize to the dominant, the subdominant, or the supertonic (V, IV, ii) of the primary key. For example, in A major, the secondary key would be the dominant–E major–so the secondary dominant would be the dominant of E major–B major. So, if you're looking at a piece in A major and you see II chords popping up, then you may want to consider the idea that you are looking at a tonicization.
The reason why we usually have the chord leading into the temporary tonic as a dominant chord is that we want listeners to hear the temporary tonic as a tonic. Since the leading tone in dominant chords have a strong tendency to resolve to the tonic, the leading tone in these “temporary” dominant chords have a strong tendency to resolve to the temporary tonic.
Secondary Leading Tone Chords
Remember from previous lessons that the vii० has a very similar function to the V chord: they both serve a dominant function that creates a cadence when resolved to the I chord. So, just like V chords, it is useful to use a secondary leading tone during tonicization. These chords usually appear as seventh chords: vii०⁷ and viiø⁷. Note that in a major key, you can use both vii०⁷ and viiø⁷, but in minor keys, you should only use vii०⁷. Usually, fully diminished seventh chords are more common.
Example: Write vii०/IV, vii०⁷/IV, and viiø⁷/IV in B major.
In B major, the root of the IV chord is E, so our new tonic is E. That means that our new leading tone is D#. So, vii०/IV is D#-F#-A♮, vii०⁷/IV is D#-F#-A♮-C♮, and viiø⁷/IV is D#-F#-A♮-C#.
Identifying Secondary Leading Tone Chords
Identifying secondary leading tone chords is a similar process as identifying secondary dominant chords. Start by looking for accidentals. If you see any accidentals, you should consider that you're looking at a secondary dominant.
Second, is this chord a diminished or half-diminished chord? Here's a little secret: College Board only tests on secondary dominants and secondary leading tone chords. V chords are (almost) always major, so if you're looking at a diminished/half-diminished chord with accidentals, then you're looking at a secondary leading-tone chord.
Let's look at another example. Try to analyze the chords in Brahms' Intermezzo, op 119 no. 3 in C major
Start by looking at measure 1 of the excerpt. On beat 1, the bass clef has a broken G major triad, and the treble clef has an F. (C is a passing tone) So, beat 1 is a V⁷ chord. On beat 2, there is a I⁶₄ chord, which is a passing 6-4 chord.
In measure 2, we have something interesting. On beat 1, we have a ii०⁶₅ chord (F-Ab-D-C), and on beat 2, we have F#-A-C-E, which is a diminished 7th chord. Since there are accidentals, we know that we might be dealing with a secondary leading-tone chord. F# is the leading tone for G, which is V of C, so we can write the chord in beat two as vii०⁷/V.
Why didn't we analyze beat one as a secondary leading tone? The notes on beat one are F-Ab-D-C, which means that the secondary leading tone would be in an inversion: we would write it as a 6-5 chord. And, since D is the leading tone of E, we could write it as a vii०⁶₅/iii. However, there are two problems with this. First, we usually don't see secondary leading tone chords in inversions because it erases the dominant function of the chord.
Second, musical context is important. If this were a tonicization, we would expect it to resolve to a iii triad. However, we "change key" again in beat 2 of the measure. That means that the chord doesn't serve a function as a chord in a secondary key, so we wouldn't analyze it as such.
Finally, in measure 3, we see another V⁷ chord, which makes sense musically because a vii०⁷/V is resolving to a V⁷. The last beat is another passing 6-4 chord.
Part Writing Secondary Leading Tone Chords
With secondary leading-tone chords, it's important to follow all voice-leading rules that you have learned in previous chapters. Keep in mind that, in tonicization, you'll have a different temporary leading tone, chordal seventh, and tonic. So, if we are in C major, the chordal seventh won't necessarily be F—it will be the 4th scale degree in whatever our temporary key is.
There are a few extra considerations to keep in mind when part-writing with secondary leading tone chords. First, you can't have a half-diminished 7th chord in minor because, in a minor key, we want to raise the leading tone to emphasize the dominant function of the vii°. Second, in minor keys, we don't build vii°/III or viiø⁷/III because these sound the same as ii° and iiø⁷. We also don't have viiø⁷/V, because then, we would have to both raise and not raise the leading tone in the same chord, which doesn't work.
Just like how root position viio7 chords are generally not considered acceptable in 18th century voice leading, secondary viio7 chords in root position should also be avoided if possible. Also, keep in mind that when you’re adding accidentals, we have a half diminished vii7 chord in Major, but we have a fully diminished viio chord in minor, since the interval between the fifth and the seventh of a vii7 chord in Major is a Major 3rd (e.g. the interval between F and A when writing a vii7 chord in C Major), but the interval between the fifth and the seventh of a vii7 chord in minor is a minor 3rd (e.g. the interval between F and Ab when writing a vii7 chord in C minor).
Remember that the leading tone should always be raised when writing these secondary leading tone chords. The whole point of using a secondary leading tone chord is to build tendency tones that resolve to the temporary tonic, so it would not be considered to have VII or VII7 chords in a secondary leading tone chord.
Tonicizing Deceptive Motion
Often, we might have a deceptive cadence, but there will be a tonicization of the deceptive cadence in order to “resolve” the deception. For example, we might move from a V to a vii/vi to a vi chord in Major. Why is this so common?
A vii/vi chord just has the root of the V chord, which means that the motion from the V chord to the vii/vi chord will have many common tones – we will just diminish them. Thus, when moving from the V-vii/vi chord, there will be mostly stepwise motion, and the chord will sound like a non-chord tone.
And, the vii/vi to vi cadence will sound more conclusive than a V-vi cadence, because we have the vii-i motion in the secondary key (in this case, the secondary key is built in the sixth scale degree).
Let’s look at an example of this:
This is an excerpt from a piece called “Mag da draussen senhee” by Josephine Lang.
In this case, we are moving from a V7 in the primary key to a viio7 in the secondary key of Bb. The chord tones for the V7 are Ab-C-Eb-Gb, which are arpeggiated in the upper voices. Next, in the viio7/vi, the chord tones would be the chord tones of the viio7 in Bb minor, which are A natural - C-Eb-Gb. Note that even though this chord is in root position, it is usually not considered good practice to write a root position viio7 chord in 18th century voice leading. The leading tones in the viio7 chord resolve upwards (the As resolve to Bb), and the chordal seventh, in this case Gb, resolves down to the F, in the arpeggiation of the vi chord in Db Major.
Frequently Asked Questions
What's the difference between secondary dominants and secondary leading tone chords?
Secondary dominants and secondary leading-tone chords both “tonicize” a chord by momentarily treating it like a tonic, but they’re different formulas and behave differently in voice-leading. - Secondary dominant: is the V (or V7) of the target chord (e.g., V/V = D major in key of C). It’s built on the dominant of the chord-to-be-tonicized and often resolves by root motion down a 5th to that chord. Can be major/minor quality depending on mode. - Secondary leading-tone chord: is the vii° (diminished triad) or vii°7 (fully- or half-diminished seventh) of the target chord—built on that chord’s leading tone (e.g., vii°/V in C is built on C#). Triads appear typically in first inversion (vii°6); sevenths may be any inversion. Note: half-diminished vii°7 forms occur only when tonicizing a major triad (CED PIT-2.Q). On the AP exam you should identify both types, show correct inversions and resolutions, and watch chromatic alterations of scale degrees. Review Topic 7.3 on Fiveable (https://library.fiveable.me/music-theory/unit-7/tonicization-through-secondary-leading-tone-chords/study-guide/xfW8Oy4Pc8f8cmlLVukh) and try practice problems (https://library.fiveable.me/practice/music-theory).
How do I identify a vii°7/V chord when I'm listening to music?
Listen for a diminished seventh (or diminished triad) built on the leading tone of the V chord—in other words, the note a half step below the V’s root (vii°7/V is built on ̂̄ of the original key). It will sound chromatic compared to the home key (because scale degree altered), feel tense, and then resolve to a clear V chord. Clues: (1) you hear a fully- or half-diminished seventh sonority (stacked minor thirds); (2) the chord’s voices move by small steps so the chord tones resolve into the V (the chordal seventh usually steps down, the raised leading tone often resolves up to V’s root); (3) it functions briefly like an applied leading-tone chord before giving you V (tonicization to V). This is exactly the PIT-2.Q.3 concept on the AP exam—practice identifying these in the Topic 7.3 study guide (https://library.fiveable.me/music-theory/unit-7/tonicization-through-secondary-leading-tone-chords/study-guide/xfW8Oy4Pc8f8cmlLVukh) and with lots of aural drills at (https://library.fiveable.me/practice/music-theory).
I don't understand how to build a secondary leading tone chord - can someone explain the steps?
Steps to build a secondary leading-tone chord: 1. Pick the chord you want to tonicize (the “target” chord). 2. Find that chord’s leading tone (a half step below its root). Example: in C major, to tonicize V (G), the leading tone of G is F#. 3. Build a diminished triad (or diminished seventh) on that leading tone. Example triad: F#–A–C (vii° of V). A vii°7 would add E♭/D# depending on spelling (fully-diminished). 4. Put the diminished triad in first inversion (vii°6/target)—the triad almost always appears as vii°6. Seventh chords may appear in any inversion as context requires. 5. Voice-lead normally: the chord’s leading tone resolves up to the root of the target chord, and other voices resolve to form the target (v or V). Remember: half-diminished viiø7 only appears in major mode and thus only tonicizes major triads per the CED. This is exactly what the AP CED describes (see Topic 7.3 study guide for worked examples: https://library.fiveable.me/music-theory/unit-7/tonicization-through-secondary-leading-tone-chords/study-guide/xfW8Oy4Pc8f8cmlLVukh). For extra practice, try problems on the Unit 7 page (https://library.fiveable.me/music-theory/unit-7) or the practice bank (https://library.fiveable.me/practice/music-theory).
What does it mean when a chord "tonicizes" another chord?
“Tonicize” means briefly treating a chord other than the home tonic as if it were a new, temporary tonic. With secondary leading-tone chords, you build a diminished triad or a diminished seventh (root = the leading tone of the chord you want to tonicize) and resolve it to that target chord. For example, vii°6/V (or vii°7/V) is built on the original key’s raised 4̂ and pushes toward V; vii°7/ii is built on ̂ of the original key and pushes to ii. Tonicization usually involves a chromatic alteration (raising the scale degree that becomes the leading tone) and a short resolution to the tonicized chord. Remember the half-diminished viiø7 only appears in major mode, so half-diminished secondary leading-tone chords can only tonicize major triads. On the AP exam you should be able to identify and describe this in performed or notated music (CED PIT-2.Q). For more review see the Topic 7.3 study guide (https://library.fiveable.me/music-theory/unit-7/tonicization-through-secondary-leading-tone-chords/study-guide/xfW8Oy4Pc8f8cmlLVukh), Unit 7 overview (https://library.fiveable.me/music-theory/unit-7), and practice problems (https://library.fiveable.me/practice/music-theory).
How do I know which scale degree to use as the root of my secondary leading tone chord?
Pick the chord you want to tonicize (the target: V, ii, vi, etc.). The root of a secondary leading-tone chord is the leading tone of that target chord—i.e., one semitone below the target chord’s root, measured in the original key. Build a diminished triad or a diminished seventh (vii° or vii°7) on that pitch. Example in C major: to tonicize V (G), the root is F♯ (the leading tone of G); vii°/V = F♯–A–C (often written vii°6 when a triad appears in first inversion). Remember CED rules: triads usually appear in first inversion (vii°6), sevenths may be in any inversion, and half-diminished viiø7 is used only when tonicizing a major triad. For more examples and AP-aligned practice, see the Topic 7.3 study guide (https://library.fiveable.me/music-theory/unit-7/tonicization-through-secondary-leading-tone-chords/study-guide/xfW8Oy4Pc8f8cmlLVukh), the unit overview (https://library.fiveable.me/music-theory/unit-7), and plenty of practice questions (https://library.fiveable.me/practice/music-theory).
Why can secondary leading tone triads only appear in first inversion?
Because a leading-tone triad is built on the scale step that wants to resolve (the leading tone), putting that unstable pitch in the bass creates voice-leading and doubling problems. In root position the chord would force either a doubled leading tone (bad) or an awkward bass that must move by step to the tonicized root, making smooth four-part writing difficult. Putting the chord in first inversion (vii°6) puts the third in the bass, so the actual leading tone is one of the upper voices and can resolve up by step to the tonicized chord’s root. First inversion also lets you avoid doubling the leading tone and produces cleaner resolution into the tonicized triad. AP CED explicitly states triads appear only as vii°6 while vii°7 (or half/fully diminished sevenths) may be used in any inversion because the seventh provides the needed tones for clear resolution. For more practice and examples see the Topic 7.3 study guide (https://library.fiveable.me/music-theory/unit-7/tonicization-through-secondary-leading-tone-chords/study-guide/xfW8Oy4Pc8f8cmlLVukh) and Unit 7 resources (https://library.fiveable.me/music-theory/unit-7).
What's the difference between fully diminished and half-diminished secondary leading tone chords?
Fully diminished vs. half-diminished secondary leading-tone chords—short answer: - Quality: a fully-diminished seventh (vii°7) is a diminished triad plus a diminished seventh (stack of three minor thirds). a half-diminished seventh (viiø7) is a diminished triad + a minor seventh (diminished triad with a minor 7th above the root). - Use in tonicization (CED): both kinds can tonicize a target chord by being built on that chord’s leading tone. But the half-diminished seventh only appears in major mode contexts, so viiø7 as a secondary leading-tone chord may be used only when it tonicizes a major triad. Fully-diminished sevenths can be used more generally (major or minor targets). - Notation/voice-leading: diminished triads normally show up as vii°6 (first inversion); seventh chords may appear in any inversion appropriate to voice-leading. In all cases the chord’s tendency tones resolve to the tonicized chord (leading tone → tonic, etc.). Review the AP Topic 7.3 study guide for examples (Fiveable) and practice lots of voice-leading problems (https://library.fiveable.me/music-theory/unit-7/tonicization-through-secondary-leading-tone-chords/study-guide/xfW8Oy4Pc8f8cmlLVukh; practice hub: https://library.fiveable.me/practice/music-theory).
How do I write vii°6/ii in the key of C major?
vii°6/ii in C major is the diminished triad built on the leading tone of ii (D). In C major, ii = D–F–A, so its leading tone is C♯. The vii° triad is C♯–E–G, and “6” means it appears in first inversion (third in the bass): E–G–C♯. Write it in four parts like this (one common spacing/doubling): - Bass: E (the third of the chord, doubled) - Tenor: C♯ (leading tone → will resolve up to D) - Alto: G (→ usually resolves up to A) - Soprano: E (doubling the third is safe; don’t double the leading tone) Show the chromatic alteration (C♯) in the score. Voice-leading into ii (D–F–A): C♯ → D, E → F, G → A (smooth stepwise resolutions). Remember the CED rule: secondary leading-tone triads in major appear only in first inversion (vii°6) and tonicize the target chord (here ii). For more detail see the Topic 7.3 study guide (https://library.fiveable.me/music-theory/unit-7/tonicization-through-secondary-leading-tone-chords/study-guide/xfW8Oy4Pc8f8cmlLVukh) and practice problems (https://library.fiveable.me/practice/music-theory).
I'm confused about when to use half-diminished vs fully diminished secondary leading tone chords - help?
Use the leading-tone quality that fits the chord you’re trying to tonicize and the mode of the target triad. Key points from the CED: - A secondary leading-tone triad (vii°) is a diminished triad and appears in first inversion (vii°6) when functioning as a tonicization, just like a normal vii°. - For seventh chords, use either fully diminished (vii°7, with a diminished seventh) or half-diminished (viiø7, minor seventh) depending on the target chord’s mode: half-diminished secondary leading-tone seventh chords are used only to tonicize major triads; fully-diminished sevenths can tonicize major or minor triads. - Remember these are built on the leading tone of the chord being tonicized, so you’ll usually need a chromatic alteration of a scale degree to make that raised leading tone and then resolve to the tonicized chord (often V or ii). This is exactly what the Topic 7.3 study guide explains (https://library.fiveable.me/music-theory/unit-7/tonicization-through-secondary-leading-tone-chords/study-guide/xfW8Oy4Pc8f8cmlLVukh). For more practice, check Unit 7 and the practice problems (https://library.fiveable.me/music-theory/unit-7 and https://library.fiveable.me/practice/music-theory).
Can I use secondary leading tone chords to tonicize minor chords or just major ones?
Short answer: Yes—secondary leading-tone chords can tonicize both major and minor chords. The CED says applied leading-tone triads or vii°7s may target any major or minor triad; the diminished triad form appears in first inversion (vii°6) and vii°7 (fully or half-diminished) can be used in appropriate inversions. One important restriction: the half-diminished seventh (viiø7) only occurs in major mode, so a secondary leading-tone chord that’s half-diminished can only tonicize a major triad. Otherwise, use a fully diminished vii°7 (or a diminished triad) when tonicizing a minor chord (with the required chromatic alteration of the tonicized chord’s leading tone). For more examples and AP-aligned practice, check the Topic 7.3 study guide (https://library.fiveable.me/music-theory/unit-7/tonicization-through-secondary-leading-tone-chords/study-guide/xfW8Oy4Pc8f8cmlLVukh) and Unit 7 overview (https://library.fiveable.me/music-theory/unit-7); you’ll find practice problems at (https://library.fiveable.me/practice/music-theory).
How do I analyze secondary leading tone chords in Bach chorales for my portfolio?
Scan the passage for a temporary tonic (the chord that sounds like it’s being tonicized—often V or ii in Bach). Ask: is there a diminished chord whose root is the leading tone of that temporary tonic? If so, label it as a secondary leading-tone chord (use Roman numerals with a slash: e.g., vii°6/V or vii°7/ii). Remember CED rules: diminished triads appear as vii°6 (first inversion); seventh versions can be in any inversion; half-diminished viiø7 only tonicizes major triads because of mode restriction. Check the chromatic alteration (which scale degree is raised), follow voice-leading—the leading tone should resolve up to the tonicized chord’s root and other voices move by step—and confirm the chord resolves to the tonicized chord (not necessarily to the home key). On the AP exam you’ll be asked to identify/describe these in notated/performed music (PIT-2.Q). For extra practice, review the Topic 7.3 study guide (https://library.fiveable.me/music-theory/unit-7/tonicization-through-secondary-leading-tone-chords/study-guide/xfW8Oy4Pc8f8cmlLVukh), the unit overview (https://library.fiveable.me/music-theory/unit-7), and do more problems at https://library.fiveable.me/practice/music-theory.
What's the proper way to notate secondary diminished seventh chords in different inversions?
Write the secondary chord with a prefix showing the target chord, then the usual leading-tone symbol and inversion. Key points from the CED: - A secondary diminished triad is written as vii°/X but in practice the triad only appears in first inversion: vii°6/X (e.g., vii°6/V). That first-inversion rule is an AP requirement (PIT-2.Q.3). - Secondary diminished seventh chords may appear in any inversion appropriate to context: vii°7/X (root), vii°65/X (1st inv), vii°43/X (2nd), vii°42/X (3rd). Use the ° for fully diminished, ø for half-diminished when needed. - Remember: half-diminished secondary leading-tone chords occur only when tonicizing a major triad (because half-diminished viiø7 only appears in major mode). - Notate the chromatic alteration (raise the leading tone of the tonicized chord) above the chord if needed in figured or Roman analysis. For a quick refresher, see the Topic 7.3 study guide (https://library.fiveable.me/music-theory/unit-7/tonicization-through-secondary-leading-tone-chords/study-guide/xfW8Oy4Pc8f8cmlLVukh) and the Unit 7 overview (https://library.fiveable.me/music-theory/unit-7). Practice examples are at (https://library.fiveable.me/practice/music-theory).
Why does my ear training always trip me up on secondary leading tone chords vs regular diminished chords?
Your ear trips up because secondary leading-tone chords and regular diminished chords share the same sonority (diminished triad or dim7), so isolated sound alone isn’t enough. The AP CED expects you to ID these by function and context: a secondary vii° (usually in 6) is built on the leading tone of a chord being tonicized and resolves to that chord (v or ii, etc.). Listen for two big clues: 1) chromatic alteration—a raised scale degree that doesn’t belong to the home key (the root of the applied vii is the leading tone of the tonicized chord), and 2) bass/context—secondary vii° often appears in first inversion (vii°6) and resolves stepwise to the chord it tonicizes. Seventh-chord voice-leading (the seventh resolving down by step) is another giveaway. Practice by hearing the bass/root motion and the resolution target in short progressions. For targeted drills, check the Topic 7.3 study guide (https://library.fiveable.me/music-theory/unit-7/tonicization-through-secondary-leading-tone-chords/study-guide/xfW8Oy4Pc8f8cmlLVukh) and do practice problems (https://library.fiveable.me/practice/music-theory).
How do secondary leading tone chords create that temporary key feeling in music?
A secondary leading-tone chord creates a temporary key by acting like the true leading-tone to a chord other than the tonic. It’s a diminished triad or diminished seventh built on the leading-tone of the chord being tonicized (e.g., vii°7/V → leads to V). That chord contains a chromatic alteration (the raised pitch that functions as a leading tone), strong tendency-tone resolution, and voice-leading that pulls voices into the chord you’re tonicizing. Triads usually appear in first inversion (vii°6), seventh chords in any inversion—so they sound like a mini cadence toward the target chord, giving a brief “home away from home.” On the AP exam you’ll be asked to identify/describe these tonicizations in performed or notated music (PIT-2.Q). For a focused review, see the Topic 7.3 study guide (https://library.fiveable.me/music-theory/unit-7/tonicization-through-secondary-leading-tone-chords/study-guide/xfW8Oy4Pc8f8cmlLVukh) and practice lots of examples (https://library.fiveable.me/practice/music-theory).
What are some common chord progressions that use secondary leading tone chords?
Common patterns: a secondary leading-tone chord (vii° or vii°7) functions like an applied leading tone that resolves to the chord it tonicizes. Typical progressions you’ll see on the exam: - I → vii°6/V → V → I (e.g., in C: I – F#°6 → G → C). The triad is usually in first inversion (vii°6) and the vii°7 may appear in other inversions. - I → vi → vii°7/ii → ii → V → I (tonicize ii briefly). - ii → vii°6/V → V → I (predominant → applied leading-tone → dominant → tonic). - I → vii°7/vi → vi (tonicize vi), or I → vii°7/III → III in minor modes. Remember CED rules: secondary leading-tone triads occur as diminished triads in first inversion; half-diminished viiø7 forms only tonicize major triads (major-mode restriction). For practice and more examples, see the Topic 7.3 study guide (https://library.fiveable.me/music-theory/unit-7/tonicization-through-secondary-leading-tone-chords/study-guide/xfW8Oy4Pc8f8cmlLVukh), the Unit 7 overview (https://library.fiveable.me/music-theory/unit-7), and 1000+ practice items (https://library.fiveable.me/practice/music-theory).