The annual report describes the major activities and accomplishments during the first year (October 2017 through September 2018) of Mathematica’s contract to conduct the cross-site evaluation and provide evaluation technical assistance (TA) for the fourth cohort of Regional Partnership Grant (RPG) projects, referred to in this report as RPG4. The report provides a brief history of the RPG cohorts, information on the RPG4 projects, a summary of highlights from the first year of the contract, and a description of next steps for the second year and beyond. The report also describes Mathematica’s major activities for Year 1 of the RPG4 contract, which include (1) designing the cross-site evaluation, (2) preparing for data collection, (3) conducting evaluability assessments, and (4) providing evaluation TA to RPG projects.