We analyze the role of the marriage contract. We first formalize three prominent hypotheses on why people marry: marriage provides an exogenous payoff to married partners, it serves as a commitment device, and it serves as a signaling device. For each theory we analyze how a reduction in the costs of divorce affects the propensity to divorce for couples at any given duration of marriage. We then use individual marriage and divorce certificate data from the United States to bring these alternative views of the marriage contract to bear on the data. We exploit variations in the timing of the adoption of unilateral divorce laws across states to proxy a one‐off and permanent reduction in divorce costs. The results suggest that the dominant reason that couples enter into a marriage contract is that it serves as a commitment device.