Active parental consent policies have been blamed for low participation rates and selection bias (i.e., loss of "high-risk" youths) in school-based studies. In this article, the authors describe active consent procedures that produced an overall active consent rate of 79% in a sample of more than 4,500 middle school students attending 29 schools in seven cities across the United States. Consent rates, however, varied considerably both within and between schools. To better understand factors associated with active parental consent rates, the authors examined district-level, school-level, and teacher-specific effects on consent rates. (Contains 6 tables, 1 figure, and 12 notes.)