My Old Man contains many of the compositional elements that would become Joni's trademarks through her career. These include melodic and harmonic chromaticism, triads played over bass notes that are not the  root notes, and temporary modulations of key, often in rapid succession.


Note the very interesting journey the bridge takes us on from the home key of A through the keys of F# and B in the space of a few bars,the major/minor ambiguity between the tonalities of A and Am (bars 11/12) and C# and C#m (bars 26/27). The very exotic G#min13 chord ("and when he's gone, me and them lonesome blues collide") and the Lydian mode she employs on the F# it resolves to are very early glimpses of her jazz sensibility.


Oddly, the last 4 bars of the coda are rather childlike and pianistically rudimentary, in contrast with the sophistication heard earlier in the tune.