This editorial introduction describes the aims and scope of the special issue of the ACM Transactions on Interactive Intelligent Systems on Behavior Understanding for Arts and Entertainment, which is being published in issues 2 and 3 of volume 5 of the journal. Here we offer a brief introduction to the use of behavior analysis for interactive systems that involve creativity in either the creator or the consumer of a work of art.We then characterize each of the five articles included in this first part of the special issue, which span a wide range of applications. © 2015 ACM.