The article examines the function of marriage and associated incentive properties in relation to ancillary relief (often referred to as “settling up”) following divorce. Many countries have experienced growing divorce rates, a decline in marriage, increased unmarried intimate cohabitation, and the delaying of marriage and childbirth to a later age. There has also been a recent increase in the pressure to extend marriage formalities to same-sex couples. All of these changes raise questions concerning the incentive structures attached to marriage and divorce. Major incentive issues arise whenever there is public-policy debate about changing the law of marriage and divorce with associated implications for litigation. It is vital to understand the economics underlying the debate since there is a danger that well-meant reform might lead to adverse unintended consequences.