Cultivating alliances between specific sectors or fields with unrealized synergies is a promising strategy for systems change. Social network analysis is a useful tool for assessing whether such alliances build relationships between these previously disparate organizations. Two waves of valued network data were collected from the members (N = 25) of a justice system reform coalition composed of two types of community-based organizations: those involved in restorative justice practice and those involved in grassroots community organizing. Social network homophily analyses were employed to characterize the impact of alliance participation on relationships over time across three domains: working together, doing impactful work together, and sharing a philosophy about justice system reform. Results indicate marked increases in the prevalence of relationships between restorative justice and community organizing organizations across all domains, with the greatest increases occurring in perceptions of shared philosophy. Network structures at each time point differed by relational domain and organization type. Findings suggest that the alliance strengthened relationships between restorative justice and community organizing organizations, particularly in perceptions of shared philosophy, but that the magnitude of these changes varied depending on pre-existing interorganizational relationships and organization type. Findings challenge the idea that close working relationships between diverse members is critical to coalition effectiveness, pointing instead to the value of ambidextrous networks and alignment in members’ philosophy and vision.