The purpose of this study was to examine how teacher delivery and student progress influenced preservice teachers' perceptions of overall teaching effectiveness. Experienced teachers ("n" = 6) were videotaped teaching mini applied lessons under four conditions: (a) high teacher delivery and more student progress, (b) high teacher delivery and less student progress, (c) low teacher delivery and more student progress, and (d) low teacher delivery and less student progress. Preservice teachers ("n" = 75) viewed these teaching excerpts and rated each for teacher delivery, student progress, student musicianship, teacher knowledge of subject matter, and overall teaching effectiveness. Participants rated teachers with high delivery as more effective than teachers with low delivery, irrespective of student progress. There was a moderate positive correlation ("r" = 0.53) between perceptions of teacher delivery and student progress. Results of a multiple regression analysis revealed that teacher delivery was the best predictor of perceptions of overall teaching effectiveness, followed closely by student progress.