Most of the time when you switch a major chord to a minor chord, you’re using what’s called a modal mixture, or “borrowed chord.” The most common switch is the change from a major IV-chord to a minor iv, like this:
I vi IV iv I (C Am F Fm C)
It adds a nice moody feel to a progression. There are other examples of modal mixtures: using a diminished ii-chord instead of the normally-seen minor ii-chord: I IV iii V I (C F Ddim G C).
Even if you don’t have a background in music theory, there’s a lot about chord theory you can discover and use! Several eBooks in “The Essential Secrets of Songwriting” 10-eBook bundle (plus the free “Creative Chord Progressions”) show you exactly why chords work the way they do, and then show you how to use them in your own songs.
One that’s trickier to use, but can be kind of interesting, is, for songs in a major key, using a minor tonic chord instead of the major tonic you expect to hear. You hear a good example of this in The Bee Gees “Sacred Trust“, which starts out with a major tonic, then switches to a minor tonic before moving on:
I i ii I (C Cm Dm C)
What makes the minor tonic hard to use is its startling switch of moods. If just thrown in haphazardly, it can make it difficult to give your progression a good sense of direction. But I believe it works well in “Sacred Trust” because the listener hears the 3rd of the I-chord (E) in the C chord, then they hear the Eb of the minor tonic, and then the next chord is Dm. So there’s a hardly-noticeable E-Eb-D chromatic line that’s really charming.
If you’d like to do some experimenting with minor tonic chords in your major key progressions, here are some to experiment with:
- C F Dm Cm7 F G C (I IV ii i-min7 IV V I)
- C G Am G/B Cm G/B C (I V vi V6 i V6 I)
- C Dm G F Dm Cm G C (I ii V IV ii i V I)
- C Cm Ddim7 G C (I i iiø7 V I)
- G G7/F C/E Cm/Eb Dm G C (V V4-2 I6 i6 ii V I)
Looking for lists of progressions you can use in your own songs? “The Essential Secrets of Songwriting” eBook Bundle has 2 main collections, plus eBooks on how to harmonize your own melodies, and more.