This research study examines the extent and ways in which the first three Cohorts of MSP Partnership projects have sustained the accomplishments made during their respective grant periods. The study addresses two interrelated research questions: 1) What strategies did the initial cohorts of MSPs use to sustain and nurture their outcomes beyond their NSF award? and 2) What were the mediators that either facilitated or hindered projects' efforts to sustain these outcomes? Guided by a logic model that lays out a proposed theory of sustainability, the study uses a mixed method approach to investigate factors influencing those changes at both school district and Institution of Higher Education (IHE) levels. The study is conducted in two phases: Phase 1 involves document review, discussions with current and former NSF project officers, and interviews with PIs and Co-PIs to provide a broad brush examination of project sustainability. Phase 2 includes case studies in a sample of projects to provide a fuller assessment of facilitators and hindrances. The specific approach for each case study will depend on the type of practice being sustained and the partners and participants involved in the practice.