Because migration trends in the West and their consequences have sometimes served as indicators of what other regions can expect, it is important that such trends and effects be monitored and analyzed. This bulletin describes patterns of migration, assesses individual and family and social considerations in western migration, and discusses policy implications. Projective Markov modeling gives predictions of future population movements among the western states based on the assumption of stable transition percentages. Location preference studies focus on community aesthetic qualities and their associations with community size. Studies of actual migration behavior show that economic and family considerations influence migration and that migration is selective of the young, the more highly educated, and those in higher paying occupations. Social consequences of western migration are addressed from cost-benefit and community satisfaction perspectives. Substantive mechanisms that can influence migration include incentives and inducements, regulation, information dissemination, expenditures and siting decisions, enabling actions, and coordination and organization. Thirty-four tables show migration data including western region and subregion migration by wage change, sex, age, and industry from 1960 to 1965 and from 1965 to 1970; reasons for migration; and key social costs/benefits of community growth and decline. Graphs show scale effect and migration effect curves for 11 western states. (NEC)