The complexity of designing and implementing STEM educational experiences that meet the needs of a diverse population of students while also preparing them for careers in the 21st-century cannot be understated. Partnerships between the various stakeholders invested in providing such experiences may be the only way to respond to that complexity. In this chapter, we review a sample of the spectrum of business-education/community-education (B-E/C-E) partnerships to the nature, structure, outcomes, and impact of those partnerships. We also describe two such partnerships that were enacted in Kentucky and were centered around teacher externships. In order to draw the most powerful insights from the literature and the discussion of the two Kentucky-based projects, we employ a conceptual framework that includes the concept of a STEM ecosystem and the construct of communities of practice (COP). Related to the construct of COPs, we consider the nature of the border crossings that were embedded in the partnerships, the way brokers were involved in building bridges between stakeholders, and the manner in which boundary objects were utilized to connect practices across different stakeholder groups. This allows us to describe what seems to have been effective in allowing these B-E/C-E partnerships to accomplish their goals, as well as to understand the challenges that these partner- ships must overcome. The conceptual framework also allows us to point clearly to future directions with regards to both the practice and research that needs to be done around B-E/C-E partnerships.