Family systems, as normative frameworks in which family processes unfold, are believed to exert a major influence on fertility. While a number of studies have addressed family system effects on family size and the timing of births, the question of how family systems influence fertility intentions has remained largely unexplored. Because fertility intentions are often not realized, studying the pathways through which these intentions are framed warrants further attention. Addressing this research gap, this paper explores the pathways of influence between family systems and people’s intentions to start or to extend their family in the framework of the theory of planned Behaviour. We use a path analysis to analyse data from the Generations and Gender Survey (GGS) on fertility intentions of 28,988 individuals from nine European countries that considerably vary in family systems. Regional indicators of family systems were constructed on the basis the Survey of Health, Aging and Retirement in Europe (SHARE) and incorporated in the analytical sample. The results demonstrate an important link between family systems and fertility intentions. Family systems frame people’s intentions by influencing their attitudes towards children and their ideas about existing norms regarding fertility. This influence works partly through affecting household size and partly through influencing people’s ideas about the requirements for having children. Family system effects vary between intentions to start and to extend a family. While nearness to kin decreased positive attitudes towards having children of childless respondents, having kin nearby had the opposite effect for those that were already parents.