The analytical framework proposed by Davis and Blake (1956) divides the process of reproduction into three elements: (i) exposure to the risk of pregnancy, (ii) the ability to conceive and (iii) successful gestation. This paper is concerned with the first element. Data from the 1973 National Demographic Survey of Tanzania (NDS) are used to investigate the role of marriage behavior in determining fertility levels. Coale's parameters of the age pattern of first marriage ao, k and C are translated into Im-type measures. A system of indices is developed to represent the effects of the prevalence and age patterns of first marriage, marital disruption and remarriage on fertility. Techniques for obtaining detailed information on the process of marital dissolution and subsequent remarriage are presented. The potential effects of changes in nuptia1ity patterns on fertility are discussed.