The purpose of this study was to develop and validate an observation measure designed to capture teachers' use of interactive teaching skills within the delivery of the All Stars substance use prevention program. Coders counted the number of times teachers praised and encouraged students, accepted and used students' ideas, asked questions, self-disclosed personal anecdotes, and corrected student misbehavior. These teacher behaviors loaded on three factors: classroom management, acknowledgment, and student-centered methods. Classroom management was negatively related to student engagement. Acknowledgment was negatively related to students' normative beliefs. Student-centered methods were positively related to student idealism and normative beliefs, and marginally predicted decreases in student marijuana use. "Editors' Strategic Implications": The authors provide a promising approach to studying pedagogical prevention approaches, and they also link teaching processes to student outcomes. This study of program delivery should be of general interest (i.e., not limited to substance use prevention) to practitioners and researchers.