The study of labor flows across labor markets is a central ingredient in any discussion of labor market equilibrium. These labor flows help markets reach a more efficient allocation of resources. This paper surveys the economic analysis of immigration. It investigates the determinants of the immigration decision by workers in source countries and the impact of that decision on the host country's labor market. The survey stresses the ideas and models that economists use to analyze immigration, and delineates the implications of these models for empirical research and for our understanding of the labor market effects of immigration.