ABSTRACT While research indicates that social trust might benefit societies’ political and economic development, the sources of social trust are subject to debate. This article investigates a less investigated factor in the development of social trust: how far the nuclear family – that is, partnerships and parenthood – affects trust towards other people. The data are from three waves of the German Socio-Economic Panel study collected between 2003 and 2013. Longitudinal estimates indicate that having any number of children increases trust towards others while being partnered has a negative effect on social trust. Both effects are near-linear over the 19-year life course period investigated. The positive effect of parenthood is much stronger than the negative effect of partnership. These results are consistent across genders and ages. They indicate that social trust can change, but that it changes slowly during an adult's life. The results are discussed in relation to the social roles of adult members of nuclear families, including their activities in various social arenas.