Abstract. There have been two main arguments concerning the effects of family relationships on social trust. The first claims that the intensity of the family relationship reduces the capacity of the family members to interact in the outside world, where social uncertainty prevails. The second considers that trust inside the family spills over into trust in strangers. There is a corollary to the first argument: intense family relationships, by reducing social trust, affect community development negatively. In this article, I show, first, that it is the intensity of family relationships, and not trust in the family, that negatively affects social trust, and, second, that there is an interaction effect between trust in the family and state efficacy on social trust. While high trust in the family and low trust in strangers can go together, the relationship is spurious. It is low state efficacy that causes low trust in strangers and, to a lesser extent, high in-family trust. These arguments are tested with a sample of 44 countries from the 2005 wave of World Value Surveys.