Research indicates the continuance of a rising trend in cohabitation among heterosexual couples. Although most cohabitors eventually marry or break up, there is a subset of cohabitors that are consciously committed to remaining unmarried. Based on interviews with 45 committed unmarried heterosexual couples residing in the United States, this study investigates the reasons why some choose to abstain from legal marriage altogether. Participants indicate a variety of reasons for forgoing legal marriage, including political views, economic practicalities, divorce concerns, and a lack of rationales or incentives to marry. The reasons offered fit into two larger categories: unease about the meanings associated with marriage and concerns about what marriage does to the relationship. As a subset of cohabitors often overlooked in research, it is important to understand what motivates some into saying “I Don’t” to legal marriage.