Previous research has shown that singlehood and cohabitation are associated with postponement of parenthood. This study examines whether this association extends to the long term, potentially leading to a higher likelihood of ultimate childlessness among those with singlehood or cohabitation experience. Results from analyses of retrospective life course data from a sample of people born since 1935 and living in the Netherlands show that experience with nonmarital living arrangements has a long-term impact on the transition to parenthood. This impact is greater for females than for males and is partly caused by the higher likelihood among cohabitors to end their partnerships.