Based on the theory of teaching as assisted performance (Tharp and Gallimore, 1988), the Utrecht University Law School has implemented college teaching focusing on a particular combination of various methods of assisting students' performance. In addition to the conventional case method in legal education, the problem method was adopted as the primary method of instruction. This method focused on how students learn to solve legal problems by actually finding, framing, and analyzing issues themselves. Contingency management was used to motivate students to complete problem-solving assignments and attend the seminars in which training was provided for legal problem-solving skills. Analyses of variance were performed to examine the relation between the problem and the case method, and students' time-on-task and achievement. The results were favorable to the problem method: Compared to the case method, students spent more time on learning activities and performed better, controlling for the analysis for their previous achievement, time-on-task in previous terms, and motivation for the particular course. The differences in achievement between both teaching methods were mainly related to the difference in the time students spent on the particular course.