Background: School-based health centers (SBHCs) can integrate health and educational services to achieve common goals of student wellness and success. As no method exists to quantify the degree of integration for clinics and partner schools, this study aimed to design such a measure. Methods: Measure items were drafted from the literature. Eleven school health experts from Los Angeles, CA, used a modified Delphi method to reach consensus around items for inclusion in a School Health Integration Measure (SHIM), evaluating each on its appropriateness, substantivity, and feasibility. Twenty-eight staff at 17 SBHC campuses pilot tested the SHIM to examine its psychometric properties. Results: From 36 items, the expert panel utilized 4 rounds to reach consensus on 12 items across 5 domains: health authority, integrated programming, marketing and recruitment, shared outcomes, and staff collaboration. In the SHIM pilot, scores ranged from 2.25 to 5 (possible 1-5, mean 3.53). The measure had high internal consistency (alpha = 0.9385) and was associated with participants' general assessment of integration at their sites (p = 0.001). Conclusions: The SHIM provides a new tool to quantify health and educational service integration at SBHC sites, drive practice improvement, and test whether integration leads to better student outcomes.