“Night and Day” is a commonly played jazz standard in jam sessions, cocktail piano settings, and on many popular jazz recordings. In this article we’re going to examine a few chord substitution ideas that you can sprinkle into your playing on Night and Day to create your own arrangement and get closer to that professional, advanced jazz sound. #1: Reading the Lead Sheet (measures 1-4) Night and Day starts out with a ii-V-I progression in the key of C major, but what’s unique about this progression is that the “ii” chord is actually a “minor 7, flat 5” chord (i.e., D minor 7 flat-5). So this is really a ii-V-I in minor mode, but it resolves to C major (not C minor). #2: Filling In the Harmony Filling in the harmony for Night and Day means that we’re building up the chords to include chord tones (root, 3rd, 5th, and 7th) and extensions (9ths, 11ths, 13ths). There are many possibilities for how to do this, but let’s start with a fairly basic approach that includes the melody harmonized by chord tones across both hands. #3: Substituting a Chord A common chord substitution that is used when playing Night and Day occurs in the very first measure and removes the D minor 7th chord. In its place we’re going to insert an Ab major 7th chord. Of course, we are going to leave the melody unchanged, so the “G natural” no longer functions as the 11th (on D minor 7 flat-5) but rather as a major 7th. Again, we are going to fill in the remaining chord tones to create a complete Ab major 7th chord. #4: Inserting A “Turnaround” Chord Because measures 5-8 are the same melody and chords as measures 1-4, a common jazz device is to insert a “turnaround” chord - a chord that we can use to help bring us back to the Ab major chord in measure 5. We’ll insert this chord in measure 4. The question is, “What chord can we put into measure 4 that will bring us back to the Ab major 7th chord in measure 4?” There are 2 options. Option #1: We can insert the V7 of our “target chord.” In other words, if we’re trying to get to Ab major, we’ll want to use the V7 chord of Ab, which is Eb7. Option #2: We can insert the tritone substitution of Eb7, which is A7. The tritone is an interval (a diminished 5th or an augmented 4th). The tritone substitution works by building a dominant chord a tritone away from the original dominant chord. Notice that the guide tones (the 3rd and 7th) of both the A7 and Eb7 chord are the same (“G” and “Db/C#”). #5: Improvisation Tips Each of these chord substitutions affects the chord scale we might use for improvisation. For example, if we choose to play an Ab major 7 chord in measure 1, we can use an Ab major scale, or perhaps an Ab lydian scale. If we use the D minor 7 flat-5 chord in measure 1, using a C harmonic minor scale might be more appropriate. Check out more harmonic possibilities in this excellent lesson on Night and Day.