The relationship between multiple dimensions of childhood living arrangements and the formation of subsequent unions is investigated. Using the 1995 National Survey of Family Growth, both statuses and transitions associated with childhood living arrangements at three different stages of childhood are considered. It was found that both statuses and transitions, but not the ages at which they occur, are related to the risk of union formation. Women who experienced more transitions in childhood living arrangements and who lived with other than married, biological parents form premarital cohabiting unions faster than other women. Rates of first marriage are higher among women who lived with a stepparent, and they are lower among women who lived with a parent and that parent's cohabiting partner.