Problem-based learning (PBL), an effective educational strategy mainly used in medical and professional schools, can address many of the perceived deficiencies in undergraduate education. By working on real-world problems in small groups, students learn content in a context that motivates the higher order thinking skills often neglected in traditional pedagogy. Furthermore, the PBL approach accommodates a variety of learning styles, backgrounds, and abilities. In the medical school model, each student group has a dedicated expert tutor - a student to faculty ratio impractical at most colleges and universities. To deal with this challenge, and as part of a more general program of curriculum reform to introduce PBL into undergraduate classrooms, we propose to extend our pilot experiences with use of upper-class undergraduates as tutors/group facilitators for the problem-solving process. We plan to develop and document a new course in Tutorial Methods of Instruction to support this middle layer of a multilayered program (the overlapping contributions of faculty, graduate and undergraduate peer tutors, and students) for PBL. In addition to providing the means for using problem-based instruction at the introductory level (where it can have the greatest impact in subsequent learning) the program will provide a natural progression for attracting good students to teaching careers, and will allow them to gain an overview of their chosen major as a culminating experience prior to graduation. For students in the PBL courses, these upper-class tutors will assist with the often difficult transition between the learning culture and expectations of the high school versus college experience, particularly as they relate to the novel challenges of PBL. Documentation of the program will include an instructional manual, a professionally produced teaching video, and both short and long-term evaluation at each layer of the program. Dissemination will be achieved through publication in education journals, presentati ons at professional meetings, and workshops at our established annual conference on problem-based learning that includes precollege teachers.