Triadic closure is the common tendency for connections to emerge between people's social network ties. This phenomenon has clear implications for congregational networks and may underlie many of the social benefits associated with church involvement. Less documented in the sociology of religion, however, is the occurrence of triadic closure involving congregational and noncongregational relationships within people's close personal networks. To conceptualize this boundary‐spanning network overlap, we elaborate the concept of trans‐congregational triadic closure (TCTC). Using data from the Portraits of American Life Survey—a project that examines both general and congregation‐specific networks of U.S. adults—we consider how religious tradition, macro‐level context, and individual factors predict the occurrence of TCTC in churchgoers’ networks. Findings suggest pronounced differences between evangelicals and mainline Protestants, a considerably lower likelihood of TCTC in densely populated areas, and higher likelihoods of TCTC corresponding with long durations of congregational involvement. We conclude by noting some of the implications of TCTC for the lives of individual believers and for religious organizations, and suggest ways that this concept could elucidate further aspects of contemporary religious life.