This paper has three objectives. The first goal is to summarize the literature on same-sex families relating to the major life transitions of relationship formation, marriage, parenting, relationship dissolution, and old age. For the most part, this literature remains scant, with many areas completely ignored. Second, reasons why there is relatively little known about the life course of same-sex families will be examined. In particular, we argue that the life course’s focus on marriage as a marker for transitions, including whether or not transitions are on or off time, works to exclude same-sex families since they are not legally able to marry in most countries. The third objective is to explore if, and how, the family life course development perspective can be adapted or modified so that it can account for the diversity of both same and opposite-sex families.