Mutual reinforcement is a key concept in the two-generation field and is of interest to both researchers and practitioners. Mutual reinforcement occurs when service providers align and build on each other’s efforts to serve whole families by adopting a shared vision and working toward common or compatible goals. A valid and reliable measure of mutual reinforcement could provide actionable information specific to two-generation initiatives to strengthen their service delivery, and therefore, child and family outcomes. This brief describes the development of the Two-Generation Mutual Reinforcement Measurement Tool, the findings from a small pilot study (May through July 2022), how the tool is scored, and next steps for developing the tool. This tool is intended for research and evaluation purposes, both formative and summative. To use this tool in a formative way, two-generation initiative staff and partners from the same initiative can work together to answer the questions, generate a mutual reinforcement score using the electronic version of the tool in Appendix D at https://www.acf.hhs.gov/opre/report/two-generation-mutual-reinforcement-measurement-tool, identify areas for strengthening their initiative, and track changes over time as they work on those areas. We have designed the tool so that higher scores indicate stronger levels of mutual reinforcement. (author abstract)