Schools need effective, sustainable implementation strategies to support teachers in using effective Tier 1 (i.e., whole class) and Tier 2 (i.e., targeted) behavioral interventions in the classroom. This paper describes an iterative, community-partnered process of developing implementation resources to support teachers in using Tier 1 and 2 positive behavior management interventions; we call these resources the Positive Behavior Management Toolkit (PBMT). There were two key aspects to the iterative development process: 1) working with a Program Development Team of district--and school-employed partners to identify priorities, interpret data, provide feedback on resources, and plan for sustainment; and 2) conducting a series of tryouts in which teachers used a version of the PBMT in their classrooms and provided quantitative and qualitative feedback on acceptability, appropriateness, feasibility, and recommendations for improvement. In partnership with the Program Development Team, we used data from the tryouts to inform revisions to the PBMT. This paper presents quantitative and qualitative data from the tryouts and describes how these data informed revisions to the PBMT. We also describe the processes by which we engaged the team, considerations related to contextual appropriateness, and lessons learned related to community-engaged intervention development research.