Proponents tout licensure reciprocity as a means for alleviating teacher shortages. In this paper, we describe existing national and regional reciprocity agreements and consider the arguments underlying this proposition. We use research on teacher shortages, the reserve pool, within-state variation in demand, and teacher mobility to draw conclusions about the plausibility of this argument. Our analysis suggests that relocation from state to state has limited potential to alleviate shortages. Instead, the evidence suggests that areas of need are better defined by socioeconomic considerations than by state boundaries. A policy strategy with better potential for reducing shortages would provide incentives for teachers to work in low SES urban and rural schools.