BackgroundCommunities across the U.S. and globally confront the challenge of transforming negative social determinants of health (SDOH) into positive ones. To address this complex social problem, the collective impact (CI) approach has promise but has been critiqued for insufficiently challenging structural inequities. Research applying CI to SDOH is limited. This mixed-methods study examined early adoption of CI in the 100% New Mexico initiative that aims to address SDOH population-wide in a state with strong cultural identity and assets but also persistent socio-economic inequality.MethodsA web-based survey, interviews and focus groups were conducted with initiative participants in June and July 2021. Survey participants rated agreement on a 4-point scale with six items assessing CI foundation adapted from the Collective Impact Community Assessment Scale. Interviews and focus groups centered on motivation to engage, progress achieved in model components, CI core conditions, and contextual factors influencing experiences. Surveys were analyzed using descriptive means and proportions. Qualitative data were analyzed using thematic analysis and an inductive approach followed by stratified analyses and co-interpretation of emergent findings with model developers.ResultsFifty-eight participants completed the survey, and 21 individuals participated in interviews (n = 12) and two focus groups (n = 9). Survey mean scores were highest related to initiative buy-in and commitment, and lower related to shared ownership, having multiple perspectives and voices involved, and adequate resources. Qualitative results showed that the framework’s cross-sector emphasis helped motivate participation. Participants embraced the focus on leveraging existing community assets that is characteristic of CI and the current framework. Counties implemented effective engagement and visibility strategies including mural projects and book clubs. Participants expressed communication challenges across county sector teams which influenced feelings of accountability and ownership. Participants did not report challenges lacking relevant, available, and timely data or tension between funder-driven and community-driven desired outcomes, in contrast with previous CI research.ConclusionMultiple foundational conditions of CI were supported in 100% New Mexico, including evidence for support of the common agenda addressing SDOH, shared measurement framework, and mutually reinforcing activities. Study results suggest that efforts to launch CI to address SDOH, which is by nature multi-sector, should include robust strategies to address communication needs of local teams. The use of community-administered surveys to identify gaps in SDOH resource access contributed to ownership and a sense of collective efficacy that may portend sustainability; however, relying on volunteers in the absence of other resources extensively also threatens sustainability.Supplementary InformationThe online version contains supplementary material available at 10.1186/s13690-023-01120-4.