Marriage is central to theoretical debates over stability and change in criminal offending over the life course. Yet, unlike other social ties such as employment, marriage is distinct in that it cannot be randomly assigned in survey research to more definitively assess causal effects of marriage on offending. As a result, key questions remain as to whether different individual propensities toward marriage shape its salience as a deterrent institution. Building on these issues, the current research has three objectives. First, we use a propensity score matching approach to estimate causal effects of marriage on crime in early adulthood. Second, we assess sex differences in the effects of marriage on offending. Although both marriage and offending are highly gendered phenomena, prior work typically focuses on males. Third, we examine whether one's propensity to marry conditions the deterrent capacity of marriage. Results show that marriage suppresses offending for males, even when accounting for their likelihood to marry. Furthermore, males who are least likely to marry seem to benefit most from this institution. The influence of marriage on crime is less robust for females, where marriage reduces crime only for those with moderate propensities to marry. We discuss these findings in the context of recent debates concerning gender, criminal offending, and the life course.