The U.S. farm labor market shows many signs of tightening, including producer reports of labor shortages, increases in farm wages, more employment of guest workers through the H-2A Temporary Agricultural Program, and a shrinking supply of farm labor from rural Mexico—the source of most foreign-born farm workers in the United States. Mexico’s farm labor market has also faced labor constraints over the past several decades. Although Mexican agricultural output continues to grow, rural Mexicans are less likely to work as farm workers either in Mexico or in the United States, as the Mexican economy transitions toward more focus on the service sector. This report reviews evidence showing that rising educational levels and increased nonfarm employment in Mexico are among the leading drivers of farm labor supply changes in that country. Several options by which U.S. agricultural employers could respond to a tighter labor market are explored, including raising wages, further mechanization, greater employment of guest workers, and switching to less labor-intensive crops.