BACKGROUND: Young men who have sex with men (YMSM) have the highest rates of human immunodeficiency virus (HIV) infection in the United States. Decades into the HIV epidemic, the relationships that YMSM-serving health and social organizations have with one another has not been studied in depth. OBJECTIVES: The aim of this study was to examine the competition, collaboration, and funding source structures of multiplex organization networks and the mechanisms that promote fruitful relationships among these organizations. RESEARCH DESIGN: The study data collection method was a survey of health and social organizations from 2013-2014 in 2 cities, Chicago, IL and Houston, TX. SUBJECTS: Study participants were representatives from 138 health and social organizations. MEASURES: Responses to survey questions were used to reconstruct competition, collaboration, and combined competition-collaboration networks. RESULTS: While taking into consideration the collaborative relationships among organizations, we provide statistical evidence that organizations of similar type, similar social media use patterns, comparable patterns of funding, and similar network contexts tended to compete with one another. This competition was less likely to be accompanied by any sort of collaboration if the organizations shared common funding sources. CONCLUSIONS: Competition that excludes potential collaboration may be detrimental to mobilizing the collective efforts that serve local YMSM communities. System-level interventions may provide promising approaches to scaling-up HIV prevention and treatment efforts so as to encourage organizations to form partnerships with otherwise competing providers.