In this session we will describe the Waltham STEM Collaboratory (WSC). The WSC is focused on building and sustaining a longitudinal and district wide STEM program for middle school students. The WSC consists of (1) Waltham Public Schools, (2) Faculty from the Lynch School of Education (Drs. Barnett, Kim,, and Zhang), (3) the Lemelson-MIT invent program (http://lemelson.mit.edu/jv-inventeams), and the (4) Massachusetts Technology Leadership Council (MassTLC: http://www.masstlc.org/). We will discuss how the collaborative work directly addresses the strategic priorities for Waltham Public Schools (WPS) in STEM education. Specifically, how the work is enabling WPS to create transformative STEM experiences for all middle-school aged youth. A special focus is on youth from under-represented populations in STEM to not only participate in rich STEM experiences to but also to engage in experiences that build on their interests, prepare them for high school, and enable youth pursue STEM fields in the future.