This study of family migration and nonmarket activities in a 10% sample of 4513 families drawn from the 1973 census of Costa Rica shows that differences in family characteristics can affect a familys mobility by changing a familys costs of producing household commodities or its ability to earn income at various locations. Many aspects of the familys nonmarket production are costly to transfer to a new location. The relative complexity of family versus individual migration involves more than the simple observation that family ties increase the costs of a move. Not only does location have an impact on market income but it also plays a role in household production. Many aspects of household production may be highly region-specific such as caring for children or aged adults providing for the childrens education and enjoying the company and support of friends and relatives. Higher husbands income may not be sufficient to compensate for the costs of transferring these activities to a new location. Differences in household technology represented by the education variables of the mothers play an important role in family migration as families resist moving from an area that has low input costs in the production of those commodities for which they have a comparative advantage. Families with a comparative advantage in producing educational commodities may be more likely to move to urban areas with better school systems and less likely to move in general. The number of children and the investment in their education are negatively associated with migration. The household production model allows the roles of women to be incorporated into migration analysis. The characteristics of women appear to be important in determining household migration. Even though less than 6% of the women in the sample earn wage income they should not be ignored in migration studies. The significant negative impact of the wifes education on migration attests to the dangers of ignoring the wifes role.