On 1 January 1990, new regulations were introduced for the Swedish National Widow's Pension Scheme. The transitional provisions of the reform made it advantageous for many people to marry before the end of 1989 rather than later. The result was an abnormally large number of weddings in December 1989. This highlights the lack of firm norms that govern whether Swedish couples choose to marry or to live in consensual union. It also raises questions concerning how economic rationality works in practice. © 1991, Sage Publications. All rights reserved.