Having initial intentions to marry increases cohabitors’ likelihood of marriage, yet some cohabitors with such plans do not marry. One explanation for non-marriage may be that prior union experiences and the challenges of raising shared or stepchildren could temper initially strong marital intentions. Using the 2011–15 National Survey of Family Growth (NSFG), I examine prospective marital expectations among 531 current cohabitors in short-term unions (≤ 36 months) who report they were engaged or had definite plans to marry at the start of coresidence, focusing on prior union experiences, stepchildren, shared children, and pregnancy. A fifth of current cohabitors with initial marital intentions did not definitely expect to marry their partner, and the odds of definite expectations were lower if respondents’ partners had children from a prior union and higher if respondents were expecting a child. Prior union experiences, shared children, and the respondent’s own prior children were unrelated to expectations.