Tremendous population growth, much of it fueled by domestic and international migration, has already begun to transform large parts of the Central Valley. Although this influx of migrants is posing new environmental, economic, social, and political challenges, little is known about it or its effects on the region. In The Central Valley at a Crossroads: Migration and Its Implications, Hans Johnson and Joseph Hayes find that the valley’s migration patterns are remarkably complex and vary over time, by subregion, and according to the type of migration. They also find that each subregion has pursued policy strategies to address its specific challenges. Finally, they predict that migration patterns will continue to alter the entire valley’s character and profile for the foreseeable future.