In this paper a STEM Education Outreach (STEM-EO) Model for promoting strategic university outreach programming at Penn State University to the benefit of university, school district and community stakeholders is described. The model considers STEM-EO as a complex system involving overarching learning goals addressed within four outreach domains and multiple outreach dimensions. The STEM-EO Framework provides a visual representation summarizing the complex system of interacting elements comprising STEM-EO. The STEM-EO Goals identify core aspects of STEM learning that support STEM literacy and address challenges facing the STEM pipeline. The STEM-EO Dimensions describe the context of specific projects, defining finer-grained characteristics, such as the nature of the targeted audience(s), educational setting, and methods of instructional engagement. The combination of Framework, Goals, and Dimensions provides a detailed description of projects and a multi-level grid on which to map and understand existing projects in terms of the pipeline, domains, goals, and dimensions. It allows more accurate identification of gaps in STEM-EO programming and development of projects that will help fill those gaps. This combination also emphasizes the importance of goal/assessment driven programming while recognizing the need to consider aspects of program dimensions and influence within and across domains during goal and assessment design and interpretation of assessment data.