This paper deals with the recent widespread increase in marriage rates in the Western world. The principal materials used are data on the proportions single in each age group at various times. These data are used to estimate how far the ‘marriage boom’ has reflected decreases in the proportions of persons remaining single throughout life or reductions in the age at marriage of those who do marry. The conclusion is that changes of both types have occurred; the mean age at marriage has been declining in several countries at a rate of more than one-tenth of a year per annum. A number of ancillary technical problems relating to the analysis of nuptiality are discussed.