AbstractPrevious research has shown that parental as well as own socio-economic status (SES) influence nonmarital fertility. This chapter examines to what extent the effect of parental SES on partner status at first birth is mediated through own SES. Data from the Generations and Gender Survey, British Understanding Society Survey, Dutch Survey on Family Formation, American National Survey on Family Growth, and Canadian General Social Survey are used to examine 16 national contexts. In the majority of countries, the effect of parental SES on the likelihood of having a first birth in cohabitation and in marriage is partly explained by the intergenerational transmission of SES. A direct effect of parental SES is found in Canada, USA, Norway, Bulgaria, Estonia, Georgia, and Romania. The effect of parental SES on the likelihood of having a first birth while being single and in marriage is partly explained by the intergenerational transmission of SES. In the USA, Austria, and Norway, a direct effect of parental SES was also found. The results suggest that in addition to the intergenerational transmission of SES, differences in family aid may influence the transition to adulthood. It is also possible that parental SES influences the motivation and ability to prevent pregnancies.