The Pittsburgh Tissue Engineering Initiative (PTEI) is the applicant organization for this Institutional NRSA to support postdoctoral fellowship training in musculoskeletal tissue engineering (TE) for clinical applications in medicine and surgery. PTEI is a not-for-profit organization whose mission is to foster TE research and education regionally, nationally, and internationally. The major regional academic institutions (Allegheny General Hospital, Carnegie Mellon University, Children's Hospital of Pittsburgh, Duquesne University, University of Pittsburgh, and University of Pittsburgh Medical Center) are members of PTEI and provide the venues for TE academic research and development. PTEI supports these organizations through seed research grants and educational programs, including its Postdoctoral Fellowship Program. As well, PTEI fosters university-academic relationships with the burgeoning TE biotechnology commercial enterprise. The PTEI Postdoctoral Fellowship Program began in January 2000 and is special in that each fellow is assigned a primary and a secondary mentor, chosen from the member institutions and based on the correspondence between the mentors' expertise and the fellow's prior training and desired focus within TE. The two mentors may be in the same or different institutions. The mentors include M.D.s, D.M.D.s, D.D.S.s, Ph.D.s, and those with dual degrees; emphasis is on clinician-basic scientist pairing of mentors. The supporting facilities and didactic opportunities thus span the major academic institutions in Pittsburgh. The Fellowship is two years long, with an option for a third year. Each fellow spends 2/3-3/4 of the two-year fellowship in the primary mentor's laboratories and the rest with the secondary mentor; these assignments may be consecutive or concurrent. Additional ad hoc experiences are arranged as needed. An introductory course in starting a biotechnology company, taught at Carnegie Mellon University, and formal instruction in the responsible conduct of research are required didactic activities. The primary mentor's institution manages the administrative aspects of the fellowship, and PTEI contractually provides monetary support to that institution. The first two post-doctoral fellows began in early 2000, and the second two began in early 2001. Advertising for the third round will begin in February 2002. A local PTEI Executive Committee provides administrative oversight for the Fellowship Program, and a larger Scientific Advisory Committee is being established. Initial fellowship funding has been provided by both local and federal funding, but continuation and expansion of the program depends on wider extramural support. Musculoskeletal TE is the current major strength of PTEI's member institutions; this application, therefore, is focused on this area of TE and its clinical application.