We examined how predictive pre-course knowledge, critical thinking, attendance, course credit, and exam grades are of in-class participation. The association between exam performance and pre-course knowledge, critical thinking, participation, course credit, and attendance was also investigated. A two-level hierarchical linear model was used to examine these relationships in an undergraduate course. Students with higher critical thinking scores were more likely to participate when course credit was provided for participation than when no participation credit was available. Therefore, credit contingencies may more effectively raise participation levels of students with high critical thinking skills than students with low critical thinking skills.