Since Spring, 2020, participants in the Collaborating Across Boundaries to Engage Undergraduates in STEM Learning (NSF Award #1914869) have been testing a curricular model that seeks to boost STEM literacy through interdisciplinary teaching collaborations. Need: The increasingly interdisciplinary and complex issues facing our society require diverse, STEM-literate experts from a range of fields who can work and solve problems in collaboration. Addressing this national need requires innovative, research-based teaching practices that retain students and improve STEM learning. Hypothesis: Immersing students in interdisciplinary collaborative courses, where STEM and non-STEM students work together and with community partners to address community-identified issues, will result in deeper STEM learning for all of the students involved. Interdisciplinary collaboration emphasizes problem-solving in a gender-neutral, culturally and ethnically diverse community, and provides an engaging learning environment in which students solve real problems as a collaborative community with their peers from other disciplines. Approach: This project expands, tests and refines an innovative curricular model in which two undergraduate courses from different disciplines are taught in coordination. The instructors, goals, and outcomes of each course remain distinct, but the courses are connected by a science-focused project developed through an active collaboration with a community partner. We estimate that by the time the project is concluded, 18 faculty, more than 700 students and about 15 community partners will have participated. Our guiding questions centered upon identifying best practices for interdisciplinary, community-engaged pedagogies as well as gauging the effectiveness of the CAB model as an approach for improving undergraduate learning outcomes across all majors, including historically underrepresented student groups for those majors. Our preliminary outcomes identify emerging best teaching and administrative practices for designing, implementing and managing these kinds of collaborations. Initial student learning outcomes show evidence of increased student self-efficacy and engagement in STEM learning, but evidence from objective assessments of science literacy is inconclusive. We are thinking about ways to determine the degree to which this reflects the pandemic-related trauma and dislocations of the last two years, or whether this reflects on the model or the limitations of the instruments themselves. Broader impacts: This project contributes to educational strategies that can produce the STEM-literate workforce needed to tackle the pressing interdisciplinary problems of our time. It may also provide additional avenues for inquiry into effective strategies for assessing scientific literacy.