In AP Music Theory, a minor key is a tonality centered on a minor tonic triad, and writing in one requires alterations (most importantly the raised 7th scale degree) so the dominant chord is a major triad, a detail tested heavily in cadential 6/4 voice leading (Topic 5.6).
A minor key is a tonality whose home base (the tonic) is a minor triad. The mood is the part everyone notices, that darker, more introspective sound, but the part the AP exam actually tests is what minor keys force you to do on the page. The natural minor scale's 7th scale degree sits a whole step below the tonic, which means the diatonic chord on scale degree 5 is a minor triad. Tonal music wants a major dominant with a true leading tone, so composers raise the 7th scale degree with an accidental almost every time the dominant shows up.
This is why minor keys get their own spotlight in Topic 5.6. When a cadential ⁶₄ resolves to the dominant, the voice holding the fourth above the bass resolves down by step to the third of V. In a minor key, that third of V must be the raised leading tone, which means you have to write an accidental that isn't in the key signature. Forget it, and you've written a minor v chord, which is one of the most common error-detection traps on the exam.
Minor keys live everywhere in AP Music Theory, but they map directly onto Topic 5.6 (Cadential 6/4 Chords) in Unit 5. Learning objective AP Music Theory 5.6.A asks you to identify ⁶₄ chord types, and AP Music Theory 5.6.B asks you to apply 18th-century voice leading through score analysis, error detection, part writing, and contextual listening. Per the essential knowledge (PIT-4.E.1), the sixth and fourth above the bass in a cadential ⁶₄ always resolve down by step. In a minor key, that downward resolution lands on the leading tone of the dominant chord, and the leading tone has to be raised by accidental. So minor keys turn a routine ⁶₄-to-⁵₃ resolution into a two-part test, namely correct voice leading and correct chromatic alteration. Part-writing FRQs in minor keys reward you for remembering both.
Keep studying AP Music Theory Unit 5
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view galleryHarmonic Minor Scale (Unit 1)
The harmonic minor scale exists precisely because of the problem minor keys create at cadences. Raising scale degree 7 manufactures the leading tone that makes V a major triad, which is exactly the accidental you write when a cadential ⁶₄ resolves in minor.
Dominant Function (Unit 5)
The cadential ⁶₄ is an embellishment of the dominant, not a tonic chord (PIT-2.K.2). In minor keys, the dominant only earns its function when you raise the leading tone. A diatonic minor v has no pull back to tonic, so it can't do the dominant's job.
Tonic Function (Unit 4)
In a minor key the tonic triad is minor, and a cadential ⁶₄ contains exactly those tonic-triad notes. Don't be fooled. Same notes, different job. The ⁶₄ behaves as a decoration of the dominant, not as a return home.
Melodic Minor Scale (Unit 1)
Melodic minor raises scale degrees 6 and 7 going up to smooth out melodies headed toward the tonic. When you part-write rising melodic lines into a cadence in a minor key, melodic minor is why you raise both notes instead of just the leading tone.
Minor keys show up most aggressively in Unit 5 voice-leading questions. Multiple-choice stems repeatedly ask some version of "in a minor key, what alteration is required when a cadential ⁶₄ resolves to the dominant?" The answer is always the same idea, namely raise the 7th scale degree so the third of V is a true leading tone. The voice with the fourth above the bass steps down to that raised note. In error-detection questions, the classic trap is a cadential ⁶₄ resolving to a minor v with no accidental. In part-writing FRQs, a minor-key figured bass means the key signature won't write the leading tone for you, so you have to add the accidental yourself every time V or V7 appears. Contextual listening also leans on minor keys, since hearing the raised leading tone is how you confirm a dominant arrival at a cadence.
A minor key and the natural minor scale are not the same thing in practice. The natural minor scale is just the pitches the key signature gives you, with a whole step below the tonic. Actual music in a minor key routinely raises scale degree 7 (harmonic minor) or degrees 6 and 7 (melodic minor) to create a leading tone and a major dominant. If you part-write in a minor key using only natural minor, your V chords come out minor and the exam marks them wrong.
A minor key is a tonality built on a minor tonic triad, and its key signature alone gives you the natural minor scale with no leading tone.
In minor keys, the 7th scale degree must be raised by accidental to make the dominant a major triad, because the key signature won't do it for you.
When a cadential ⁶₄ resolves in a minor key, the fourth above the bass steps down to the raised leading tone, which is the third of the dominant chord.
Per PIT-4.E.1, the sixth and fourth above the bass in a cadential ⁶₄ always resolve down by step, and that rule doesn't change in minor keys.
A cadential ⁶₄ in a minor key contains the notes of the minor tonic triad but functions as an embellishment of the dominant, not as tonic.
The most common minor-key error on the exam is a V chord written without the raised leading tone, leaving a functionless minor v.
A minor key is a tonality centered on a minor tonic triad, built from the minor scale. On the AP exam it matters most because writing functional harmony in minor requires raising the 7th scale degree with an accidental to create a leading tone and a major dominant chord.
Whenever you write a dominant-function chord (V or V7), yes. The raised 7th scale degree is what gives the dominant its pull back to tonic, and forgetting the accidental in a minor-key part-writing exercise is a graded error. Non-dominant chords, like the III triad, keep the natural 7th.
The natural minor scale is just the raw pitches from the key signature. Music actually written in a minor key alters those pitches, raising scale degree 7 (harmonic minor) or 6 and 7 (melodic minor) so cadences work. Treating a minor key as pure natural minor produces minor v chords the exam counts as wrong.
The sixth and fourth above the bass still resolve down by step (PIT-4.E.1), but the voice with the fourth lands on the third of the dominant, which must be the raised leading tone. So a minor-key cadential ⁶₄ resolution requires an accidental that a major-key one doesn't.
No. Even though it contains the exact notes of the minor tonic triad, the cadential ⁶₄ functions as an embellishment of the dominant (PIT-2.K.2). It sits on a metrically stronger beat than the V it decorates, and you should analyze it as part of the dominant, not as a tonic return.
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