In November 2012, the Bill & Melinda Gates Foundation invested in seven innovative district-charter partnerships with "the potential capacity and commitment to accelerate student college ready rates through deep collaboration and sharing of best practices" (District-Charter Collaboration Grant Request for Proposal). These partnerships brought together traditional public school districts with individual charter management organizations (CMOs) and local charter schools (and, in some cases, Catholic schools) in Boston, Massachusetts; Denver, Colorado; Hartford, Connecticut; New Orleans, Louisiana; New York, New York; Philadelphia, Pennsylvania; and Spring Branch, Texas. All seven sites received grants intended to (1) facilitate collaboration on evidence-based solutions aligned with the Foundation's College Ready strategy; and (2) improve equity of access, resources, and accountability across district and charter schools. The grants ranged in size from approximately $2 million to $5 million. This report is the third of three interim reports that present findings from a three-year study of the implementation of the grants, which ran from December 2012 through December 2015. This implementation analysis aims to increase understanding of how collaboration and practice sharing can occur across sectors; therefore, it focuses on the collaboration activities proposed by the sites that target specific staff participants, rather than on broader Compact policy changes. This report examines implementation trajectories and related intermediate outcomes through the end of the grant period (December 2015), based on interviews and focus groups with central office administrators, school leaders, and teachers in late 2015. Specifically, findings are based on: (1) semi-structured telephone interviews with 4 to 6 purposefully selected central office administrators in the traditional public, charter, and (when relevant) Catholic school sectors in each grantee site; (2) in-person and telephone interviews with 4 to 6 leaders of traditional public and charter schools in each grantee site; and (3) focus groups and telephone interviews with 5 to 13 teachers in traditional public and charter schools in each grantee site. [For the final report, "Understanding District-Charter Collaboration Grants. Final Report," see ED568711.]