Few studies have addressed the effects of teacher education generally, no less the specific program elements necessary to prepare competent and caring teachers. As a result, to address teacher shortages in science, mathematics, and special education, alternatives to traditional preparation have been proposed, and their development has proceeded apace. In the absence of guidance from research, alternative program designs have dramatically varied, even on such fundamental considerations as program length and the amount of preparation trainees require before becoming teachers of record. However, research on teacher education is only one potential source of guidance for program design. In this article, the authors use economic research and theory to identify principles of effective design. Considerations include program location, candidate selection, program cost, financial support, program requirements, practice teaching, and mentorship. They use these principles to compare and contrast fast-track programs and programs for midcareer changers. (Contains 2 tables.)