This article uses a unique set of pooled cross-sectional and time series data to examine the annual rate of U.S. immigration during 1972–1991 from 60 source countries. One distinguishing feature of the article is that it breaks out and cross-classifies various classes of immigrants—numerically limited versus numerically exempt and new immigrant versus adjustment of status. A second distinguishing feature is that it utilizes a unique vector of variables relating to the presence and characteristics of various social programs in source countries. The models developed here emphasize the importance of both differential economic advantage and the ease with which a prospective migrant can transfer skills to the U.S. labor market. Hausman–Taylor instrumental variable estimates of the coefficients indicate that in addition to other factors, social programs in source countries are significant determinants of immigration to the U.S.A.