The paper draws attention to the profound changes that are taking place in the proportions of the population of Great Britain that are single, married and widowed at various ages. These changes are the net result of a number of demographic, economic and sociological developments, such as the decrease in mortality rates and the changing balance of the sexes. After discussing an abortive attempt to forecast the future progress of the proportions, based on changes that have taken place in the recent past, the paper describes a method of estimating the pro- portions of each sex that are likely to be found in each marital status at the various attained ages in future years if the experience of the years 1950-52 in Great Britain as regards rates of marriage, divorce, widowhood and re-marriage continue indefinitely, subject to minor modifications to ensure that the numbers of marriages, etc., for the two sexes are consistent, and that the total number of married men equals that of married women. The variations in the proportions in each marital status in Great Britain during the past thirty years and those to be expected during the next thirty years, and ultimately, if the experience of the years 1950-52 persists, are set out and analysed. It is shown that, whereas the proportion of men never marrying has up to the present been about half the proportion of women never marrying, the continuance of present trends would result in the proportion of men never marrying becoming double that for women. This notable change is to be attributed, in the main, to the effect of improved vitality in childhood in replacing the excess of women at the younger adult ages by an excess of men. It is pointed out that, in the event, this change may not be fully realised, because a net emigration of men or a net immigration of women may mitigate the relative dearth of potential brides in future; but the proportions never marrying set out in the paper show the directions towards which current conditions are tending. The consequential changes for other marital statuses are also set out and discussed. [ABSTRACT FROM AUTHOR]