Clinicians, biologists, and engineers face difficult challenges in engineering effective, cell-based composites for repair of orthopaedic and cardiovascular tissues. Whether repairing articular cartilage, bone, or blood vessel, the demands placed on the surgical implants can threaten the long-term success of the procedure. In 1998, the US National Committee on Biomechanics addressed this problem by suggesting a new paradigm for tissue engineering called “functional tissue engineering” or FTE. FTE seeks to address several important questions. What are the biomechanical demands placed upon the normal tissue and hence the tissue engineered implant after surgery? What parameters should a tissue engineer design into the implant before surgery? And what biomechanical parameters should the tissue engineer track to determine if the resulting repair is successful? To illustrate the principles, this presentation will discuss tendon repair as a model system for functional tissue engineering.