OBJECTIVE: To examine how a preexisting initiative to align health care, public health, and social services influenced COVID-19 pandemic response. DATA SOURCES AND STUDY SETTING: In-depth interviews with administrators and frontline staff in health care, public health, and social services in Contra Costa County, California from October, 2020, to May, 2021. STUDY DESIGN: Qualitative, semi-structured interviews examined how COVID-19 response used resources developed for system alignment prior to the pandemic. DATA COLLECTION: We interviewed 31 informants including 14 managers in public health, health care, or social services and 17 social needs case managers who coordinated services across these sectors on behalf of patients. An inductive-deductive qualitative coding approach was used to systematically identify recurrent themes. PRINCIPAL FINDINGS: We identified four distinct components of the countys system alignment capabilities that supported COVID-19 response, including (1) an organizational culture of adaptability fostered through earlier system alignment efforts, which included the ability and willingness to rapidly implement new organizational processes, (2) trusting relationships among organizations based on prior, positive experiences of cross-sector collaboration, (3) capacity to monitor population health of historically marginalized community members, including information infrastructures, data analytics, and population monitoring and outreach, and (4) frontline staff with flexible skills to support health and social care who had built relationships with the highest risk community members. CONCLUSIONS: Prior investments in aligning systems provided unanticipated benefits for organizational and community resilience during the COVID-19 pandemic. Our results illustrate a pathway for investment in system alignment efforts that build capacity within organizations and relationships between organizations to enhance resilience to crisis. Our findings suggest the usefulness of an integrated concept of organizational and community resilience that understands the resilience of systems of care as a vital resource for community resilience during crisis.