This article investigates the determinants of kin marriage on the basis of a large-scale database covering a major rural part of The Netherlands during the period 1840–1922. We studied three types of kin marriage: first cousin marriage, deceased spouse’s sibling marriage, and sibling set exchange marriage. Almost 2% of all marriages were between first cousins, 0.85% concerned the sibling of a former spouse, while 4.14% were sibling set exchange marriages. While the first two types generally declined across the study period, sibling set exchange marriage reached a high point of almost 5% between 1890 and 1900. We found evidence for three mechanisms explaining the choice for relatives as spouses, centering both on preferences and on opportunities for kin marriage. Among the higher and middle strata and among farmers, kin marriages were commonly practiced and played an important role in the process of social class formation in the late nineteenth century. An increased choice for cousin marriage as a means of enculturation was observed among orthodox Protestants in the Bible Belt area of The Netherlands. Finally, all studied types of kin marriage took place more often in the relatively isolated, inland provinces of The Netherlands. Sibling set exchange marriages were a consequence of the enlarged supply of same-generation kin as a result of the demographic transition.