In this paper I use a rich longitudinal database from Florida to compare the characteristics of alternatively certified teachers with their traditionally prepared colleagues. I analyze the relative effectiveness of teachers who enter the profession through different pathways by estimating value-added models of student achievement. In general, alternatively certified teachers have stronger preservice qualifications than graduates of traditional university-based teacher preparation programs do, with the least restrictive alternative route attracting the most qualified prospective teachers. Teachers who enter through the path requiring no coursework have a substantially larger effect on student achievement. In contrast, the alternative pathway that requires substantial occupation-specific human capital investment yields teachers who are less effective than either traditional-route teachers or teachers who entered the profession through other alternative pathways. These results suggest that any benefits from preservice training are overwhelmed by the adverse selection into programs that require nontransferable human capital investments.