Despite previous empirical studies which have linked social capital to a number of health outcomes, few studies have investigated sub-group specific social capital among populations at increased risk for HIV infection such as gay, bisexual and other men who have sex with men (GBM). Many GBM of color belong to constructed families in which friends refer to each other with kinship terms such as parents and children. No studies have measured social capital provisions within constructed family networks. This study developed a preliminary instrument for assessing social capital among constructed families. The network level social capital scale incorporated the following theoretical domains hypothesized to define social capital derived from network membership: social influence, multiplex ties, heterogeneity, social cohesion, trust, quality of support, and compositional quality. A cross-sectional survey administered an eight-item scale to 131 GBM who belonged to constructed families. The factor structure and confirmatory factor analysis were assessed. Reliability was evaluated using Cronbach's alpha to measure internal consistency. A final single factor solution was obtained which was comprised of six items with high factor loadings. The resulting measures were highly correlated with an alpha of 0.84 and each factor loading was well above 0.3. This study assessed the psychometric properties of a preliminary network level social capital instrument among GBM in constructed families. Future studies may utilize or adopt this scale to measure network-level social capital within other populations.