In answering the call of the American Association for the Advancement of Science (1990) that "science should be taught as science is practiced at is best," science faculty across the country have systematically begun to infuse their skills, perspectives, and experiences as scientists into the instructional approaches they select for their undergraduate classrooms. Problem-based learning (PBL), which diffused into undergraduate science instruction from the medical school setting over 10 years ago, is one of those approaches. This article presents an overview of the PBL process. It also discusses the use of PBL in the undergraduate setting as well as presents additional strategies for using PBL in large enrollment courses. (Contains 2 tables and 1 figure.)