Obesity levels among American children are increasing at an alarming rate, due in part to a lack of regular physical activity (PA). Physical education (PE) is one way to facilitate student PA. The overarching PA goal for physical educators is 50% PA for students. Self-determination theory suggests that PA levels in PE and a variety of other contexts depend upon individuals' motivation levels. The purpose of this study was to determine whether autonomy and lesson type related to children's self-determination for, and actual, PA in elementary PE. Children from four elementary schools in the southern US engaged in four different PE lessons, representing variations in teaching conditions associated with student groupings and level of task choice. Students completed a motivation scale and wore pedometers and accelerometers. Results showed no situational motivation differences, but PA differences by lesson type existed. A number of plausible explanations are presented.