The average age at marriage of women has been rising in most developing countries including India. In this paper we report on the use of case studies, surveys and anthropological methods in a rural area of South India to investigate the mechanisms involved in this change. In an area where all marriages are still arranged it was found that there had been a recent shift from bridewealth to dowry and a diminution in the proportion of all marriages occurring between relatives. The rise in the age at marriage of women was explained by a marriage squeeze resulting from changes in the age structure of the population with mortality decline, an increasing concern of parents of daughters to secure sons-in-law with education and urban occupations, and a growing concept of child dependency. There was no evidence of the rise being a conscious effort to control family size. In the immediate future some women will probably remain unmarried, but the squeeze is already being reduced by a reduction in the age gap between spouses and may be modified considerably by the end of the century as the post-1975 fertility decline affects the age structure of those of marriageable age.