This study was designed to develop the Questionnaire Assessing School Physical Activity Environment (Q--SPACE) based on student perceptions. Twenty-eight items rated on 4-point Likert scales were administered to 244 middle school students in 9 schools. Exploratory factor analysis was used to evaluate the underlying structure of the items and 2 factors were extracted: physical environment (PE) and social environment (SE). Twelve and 8 items loaded saliently on PE (e.g., gym classes available) and SE (e.g., teacher encouragement), respectively. Factor scales had alpha coefficients of .86 (PE) and .81 (SE). One-week test-retest reliabilities for the factor scales of PE and SE were .78 and .72, respectively. Differences in PE scale scores across schools and PE and SE scale scores across student school physical activity behavior (e.g., participation on school teams) provided some evidence of scale construct validity. Overall, Q-SPACE demonstrates acceptable reliability for capturing middle school students' perceptions of school physical activity environment. The factorial validity needs to be assessed with confirmatory factor analysis and invariance testing procedures. (Contains 3 tables.)