School-based physical activity (PA) interventions impact children's PA involvement and thus opportunities and associated factors for the promotion of physical activity in children need to be examined. The purpose of this study was to examine physical education teachers' perceptions of PA opportunities available to students at the middle school level and indicate associated factors that might influence these opportunities. A questionnaire survey was administered to 292 public middle school teachers in 181 schools located in the southeastern region of the United States. The results of the study indicate the need for more PA opportunities for middle school children in order for them meeting the recommended daily PA involvement of 60 minutes. In addition, there were statistically significant associations between PA opportunities and facilities availability, school location, and family support, indicating that some social and environmental factors tend to impact students' PA opportunities. (Contains 7 tables.)