ABSTRACT Ted Gioia associated the “aesthetics of imperfection” with improvised music. In an earlier article, I extended it to all musical performance. This article reconceives my discussion, offering more precise analyses: The aesthetics of imperfection is now argued to involve open, spontaneous response to contingencies of performance or production, reacting positively to idiosyncratic instruments; apparent failings in performance, and so on. Perfectionists, in contrast, prefer a planning model, not readily modified in face of contingencies. Imperfection is not toleration of errors (...) and imperfections, as Gioia assumes, but a positive aesthetic, as in Japanese wabi-sabi. Imperfections can become new styles or kinds of perfection—and so true imperfectionism is a constant striving for new contingencies to respond to. A subtler, more complex relation between composition and improvisation is proposed, in which both have broad and narrow senses. Composition involves works, usually desk produced and notated; or more generally, putting things together in an aesthetically rewarding form. Thus, improvisation is a compositional method. Improvisation and composition are interdependent; both involve structure and spontaneity. Imperfectionism is an aesthetics of performance—of compositions as well as improvisations. Improvisation is no risker, or prone to mistakes, than performance of compositions. (shrink)