Environmental public health (EPH) practitioners are faced with an increasing scope and scale of population health challenges. To address these challenges, the Great Lakes Public Health Training Collaborative developed an action learning initiative titled the EPH Inquiry Towards Communities of Practice Project to increase EPH practitioner knowledge of commonly identifi ed EPH issues and assets, increase collective action through dialogue and shared learning, and create an EPH state action plan. Fifty-fi ve local health department EPH governmental leaders and six facilitators participated, representing each of the six states within Health Resources and Services Administration Region V. A multicomponent evaluation, incorporating post-session satisfaction surveys, action learning discussion transcripts, post-session refl ections, and follow-up interviews at 6 months were completed. Results suggested that the majority of respondents found the process was somewhat or very effective in identifying state-based needs and setting an agenda for addressing EPH issues. Participants reported value in the overall process and the need for more collective learning. All states implemented at least one recommendation in their action plans. The EPH Inquiry Towards Communities of Practice Project provided evidence that using an action-learning framework could serve as a workforce development approach to help practitioners address EPH challenges.