PURPOSE: This study describes topics covered by coaches assisting teachers implementing a research-based drug prevention program and explores how coaching affected student outcomes. DESIGN: The All Stars drug prevention curriculum was implemented by 16 urban teachers who received four coaching sessions. Two coaches participated. Coaches were interviewed by investigators to assess topics covered. Students completed pretest-posttest measures of mediators and substance use behaviors. FINDINGS: The average teacher was coached on 11.7 different topics, out of a total of 23 topics. Coaching topics most heavily emphasized included: introduction and wrap up; time management; general classroom management; teacher's movement around the class; asking open-ended questions; using students' questions, comments and examples to make desired points; general preparation; engaging high-risk youth; reading from the curriculum; implementing activities correctly; focusing on objectives and goals; maintaining a focus on the task; and improving depth of understanding. Seven coaching topics were found to relate to changes in student mediators and behavior. RESEARCH LIMITATIONS/IMPLICATIONS: The current study was exploratory. Future research should explore how teachers develop the particular skills required by prevention programs and how coaches can assist them. PRACTICAL IMPLICATIONS: We postulate five levels of skill development which coaches may address: (1) fundamental teaching skills, (2) mechanics of program delivery, (3) development of an interactive teaching style, (4) effective response to student input, and (5) effective tailoring and adaptation. ORIGINALITY/VALUE: This represents one of a very few studies that explores how coaching impacts outcomes in substance abuse prevention.