The conceptual framework for School as a Protective Factorapproach was presented in a companion article in this issue of the journal. The current article describes the validation of the School as a Protective Factor-Brief (SPF-Brief), a 13-item survey measuring the 3 core constructs and 13 defining characteristics of this framework. The SPF-Brief was validated through 2 studies. The developmental study used a longitudinal design including 1349 participants who completed surveys over 5 semesters, while the validation study used a cross-sectional design with 2775 participants. Both studies included middle and high school students. Factor analysis, growth model analysis, criterion-related validation, and outcome analysis were employed. Analyses provided strong evidence supporting the reliability and validity of the instrument and conceptual framework. Higher SPF-Brief scores were associated with higher math grades, English grades, and quality of life, as well as lower rates of anxiety, depression, conduct disorder, alcohol, e-cigarette, tobacco, and cannabis use. Effect size estimates ranged from moderate to strong. These findings suggest the utility of the SPF-Brief instrument and the School as a Protective Factor framework. Together, they may offer advantages to the traditional school climate approach.