In the midst of the frenetic international development of Web and CD-ROM materials, we have chosen to step back in time to an era when personal interaction was prized and the desire to develop chemistry understanding in our students included the "real time" exchange of ideas in small groups. The result, the undergraduate-led "Supplemental Instruction" (SI) program, is a program that teaches students how to learn chemistry, rather than being a tutorial session. The program has been proven successful on the basis of student test scores and attitudes toward chemistry. In this paper, we describe the successes and future challenges of small-group SI in large lecture classes.