This is the third renewal of Chemistry-Biology Interface (CBI) training grant T32 GM08804. We have designed an interdisciplinary program for training students (and faculty) at the interface of biological, medicinal, and traditional chemistry, called the Biological Chemistry Program (BCP). The BCP began in the fall of 2000 and provides a focused, cross-disciplinary education for students at the interface of biology and chemistry. The BCP is fully integrated into the departments of Chemistry and Biochemistry (Colleges of Science and Medicine), and Pharmacology and Toxicology (Division of Drug Discovery and Development, College of Pharmacy). Students may obtain a degree in Chemistry, Biochemistry, or Pharmaceutical Sciences while following the Biological Chemistry Training Program. Students undertake graduate coursework in Chemistry and Biology, perform research rotations in at least two research disciplines, organize an annual retreat and participate in the weekly BCP Research Forum, where students and faculty present research results. Importantly, students may work with anyone in the program, regardless of departmental affiliation, allowing for true multidisciplinary research efforts. The training faculty includes 28 highly active research groups. Students remain in the BCP until graduation. There are 48 students currently following the training program, 31 of whom are training grant eligible. Of these, 16% are from an underrepresented group. Training grant slots are generally awarded for years 2 and 3 in the program, allowing training grant recipients great flexibility in assembling a multidisciplinary research project. Fellowships are awarded in May to help first- year students assemble a broad-based mentoring team. For years 15-20, we request 6 training grant slots per year. Training at the Chemistry-Biology Interface is highly relevant for advances in public health. By blending Chemistry, Medicinal Chemistry and Biochemistry, our trainees are poised to make the next breakthroughs in drug discovery, disease detection, disease prevention, and the discovery of the underlying principles governing life and disease. Our 80 BCP graduates populate both academic science centers and disease-oriented private-sector companies.