This study was designed to investigate how the classroom ecology (interactions among task systems) and program of action influence participants’ understandings of misbehavior in a middle school physical education setting. One teacher and 14 students participated in a 10-day basketball unit with 47- minute classes. Data included fieldnotes, stimulated recall using videotapes, and semi-structured teacher and student pre- and post-unit interviews. Data were first analyzed inductively by constant comparison (Strauss & Corbin, 1998) and then by using Doyle’s (1986) classroom ecology model to understand the inductively generated categories. Data trustworthiness involved prolonged engagement, member checks, and triangulation. Results indicated that the teacher’s weak managerial task system, coupled with vague and incomplete instructional tasks, interacted with a student social system grounded in various forms of talk as social tasks to support a social program of action. Both teacher and student actions jointly created a primary social vector characterizing the overall program of action.