I am playing a song in the key of D (or B minor actually, which is D), but inside of the song, the 2,3 and 6 chords are changing to major chords instead of minor chords. Bm becomes B. E minor becomes E. F#minor becomes F#. Whats happening here? Have i shifted to another key? Is it chord substitutions in some way? is it a mode or something? i'm confused. "Once Upon a December" is the name of the song.

  • Given your description, it sounds like the song switches from B minor to B major. In that case, the song is changing mode (minor to major), but not key (B).
    – Aaron
    Jan 19, 2021 at 21:06
  • thank you! that helps. Can you just switch back and forth like that whenever you want to when composing? Is that common? or is there a rhyme or reason to it?
    – michele
    Jan 19, 2021 at 21:20
  • 1
    Both. The only rule for changing keys or modes is what one finds aesthetically pleasing. There are some general tendencies for when making a switch works better or worse, but it can be done at any time of one's choosing, and it is extremely common.
    – Aaron
    Jan 19, 2021 at 21:22

4 Answers 4


I had a listen to Anastasia and it's very much in the minor. It starts in Bm then modulates up a semitone to Cm, and ends up in another shift to C#m. Adding accidentals within a key adds flavour and interest, but the song is still based in the minor.

By the way, Bm is not D. They simply share the same key signature - two sharps.


Here are the chord changes for the first half of the verse in "Once Upon a December":

Bm F# B7 E
Em Bm Em F#

The song as a whole is in B minor, which is clear just in these chord changes. However, the presence of both major and minor chords can lead to some confusion. Here's what's happening:

  1. Bm: this is the i chord -- the "home base" chord at which the song most feels at rest.
  2. F#: this is the V chord -- were the song to follow the B minor key signature strictly, this would be a minor chord; however, it is customary to make the V chord into a major chord. Even with the alteration, it is still considered part of the key of B minor. (As to why that is, I leave for another question.)
  3. B7: this is clearly not part of B minor, but it's also not part of B major, even though it has a major sound within it. This chord actually comes from the key of E, where it is the V (dominant) chord. (Note that the next chord is E). The B7 chord is what is known as a "secondary dominant" (What is a secondary dominant chord?).
  4. E: There are two ways to consider this chord. We could look at the B7 E and a (very) brief visit to ("tonicization of") the key of E major, and that would be perfectly correct. But the better analysis, IMO, is that E major is "borrowed" from B major, making it closely related to B minor. This technique is called "modal mixture". In either case, the previous B7 chord serves to intensify feeling of movement toward the arrival on the E chord.
  5. Em: This is the iv chord of B minor. It's an easy-to-hear shift from E major and helps our ears adjust back to B minor.

As a final point, it's important to understand the B, E, and F# chords as the I, IV, and V chords of B minor. The Roman numeral designations have meaning about how the chords function within the (key of the) song. To consider the song in the key of D major would mean that D is the "home base" sound, and the chords would operate in different ways as II, III, and VI chords.


Basically, whenever you encounter a non-diatonic chord, it's safe to assume that something happens with the harmonic feeling at least at that point. The same goes with non-diatonic notes in the melody, i.e. if there are accidentals, unless it's a very short embellishment. Here is a very basic example, where the non-diatonic D chord is used in a C major key context.

Non-diatonic chord and note in C major

The melody doesn't always reflect the modal change, but backing chords usually do. The example above - a "secondary dominant" D major in the key of C major - is so common that many people don't even think about it as any sort of "modal" anything, but the F note being temporarily changed to F# is a small temporary change to the intervals around the tonic. In other words, the 4th scale degree is temporarily raised to an F#, which makes the set of notes the same as in the G major or C Lydian scales. But that change only lasts for the first half of the second bar in the example. It doesn't have to mean any kind of key change, it's just a temporary change in the intervals around the tonic.

Here is the same example transposed to D. The key signature, two sharps, sets the default diatonic scale, and whenever changes are needed, they are denoted with temporary accidentals. The temporary change is canceled out by either the next barline, or an explicit natural accidental.

Same example in D major

But the melody or other notes don't necessarily have to utilize the temporarily modified scale degrees, so you might not see any accidentals.

In your example, when there's a B, E and F# major chords when you used to have the D major scale as your set of expected intervals, there's just a temporary change of modal feeling. Depending on how widely and for how long the different modal feeling stays, you might classify it as a modulation or modal interchange or modal mixture. But the term and classification between different theoretical categories doesn't really matter. It can be a subjective gray area, and argueing over what is the "correct" categorization doesn't make you understand it any better. What matters is that you can identify the possible sets of intervals you feel there is in the harmonic context around the tonic at each point.

  • thank you. that was helpful. i have just started to learn about modes, so i was wondering if that had anything to do with it, but i see what you mean about people fighting over what mode changes it actually is, etc. The theoretial categories are starting to interest me.
    – michele
    Jan 19, 2021 at 21:31
  • @michele Theoretical categories can be useful in exercises when learning, but in actual music, nobody really cares about the classifications. :) The only thing that matters is that you're able to use notes and chords which serve the piece. Jan 19, 2021 at 21:33

There is really no way to know exactly what is happening without the melody. If there are accidentls in the melody then clearly there is a key change, even if momentarily. However it could also be an example of a cycle extension. This is very common and also happens the other way, i.e. major changing to minor. As an example the 3 chord is the V of the 6 chord (relative minor), so making the 3 major provides the right harmony to create a resolution to the 6 chord. In All Of Me the changes are C, E7, A7, D-7, in the key of C major. The entire string of chords hints at landing on D minor. The melody also has the G# over the E7 chord, but even if it didn't the E7 would be a nice extension before moving to A (maj or min). Think of all the places the 2, 3, and 6 chord can move to. 2 goes to the V chord, so a 2 Maj would act as the V or V in the original key. The 3 chord is the V of 6, and the 6 chord is the V of 2. You have a circle of 4ths moving from iii --> vi --> ii --> V --> I, and one commonly encounters, III7 --> VI7 --> II7 --> V7 --> I in Jazz rhythm changes. You can even slip them in right before the change,

iii --> (III7, vi) --> (VI7, ii) --> (II7, V)... etc

Even is there are no accidentals in the melody this device can create a lot more harmonic texture to the arrangement of a song.

Going the other way one frequently encounters the Amen cadence IV --> I modified with a iv chord creating a chromatic walk down, IV --> iv --> I.

So the presence of the majors on a minor, or minor on a major can be there for different reasons.

  • In All of Me, I don't hear the E7 leading towards Dm. Maybe we've played it so oftenthat's what we expect, but E7 only leads to A(7). It could be considered V/V/i, but the relationship between E7 and Dm will only work with the stepping stone of A7 to bridge the gap. Could have gone to Am and stayed there.
    – Tim
    Jan 20, 2021 at 8:27
  • I didn't mean to imply that. It leads to A which leads to D. I tend to take wide angle view of progressions when listening. D7 to A7 does not sound resolved to me but the entire sequence lands nicely on Dm
    – user50691
    Jan 20, 2021 at 11:02
  • It could have gone to... but didn't and that's important.
    – user50691
    Jan 20, 2021 at 11:46
  • I guess you meant E7 (not D7) to A7. If you did, it wouldn't sound resolved - two reasons - dominant chords, and moving I>V. A7>Dm of cousre works - V>i.
    – Tim
    Jan 20, 2021 at 12:26

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