This report discusses the findings from a three-year study of the California State University STEM Collaboratives project, funded by the Helmsley Charitable Trust. The project selected eight CSU campuses to rethink the ways in which they support first-generation, low-income, and underrepresented minority students in science, technology, engineering and math as they transition to college and experience their first year. Each participating campus implemented three integrated high-impact practices, or HIPs, through collaboration among faculty and student affairs. The three HIPs were a summer experience, a first-year seminar or first-year experience, and redesigned introductory STEM courses. Some of the key takeaways from the mixed-methods case study that examined project implementation across all eight sites include: (1) Elements of underserved, STEM student success are locked into separate silos--academic affairs and student affairs--that almost never connect, which leads to the creation of interventions that almost always meet only half of the demands that underserved, low-income, and underrepresented minority students in STEM face; (2) Specific interventions matter less than the integration of multiple support programs; (3) The study and project identified the importance of a unified community of support that can break the typically negative climate that many first-generation, low-income, and URM students face in STEM; (4) Cohorting students into the same shared experiences and courses developed a strong sense of belonging for students; and (5) For all the value that the STEM Collaboratives program had for students, it also had a great value for faculty, staff, and the broader campus communities at the participating CSU campuses. Recommendations on how campuses, state higher education systems, policymakers, and funders can act on the study findings conclude the report.