Educators are increasingly pressured to raise standardized test scores under the No Child Left Behind (NCLB) Act of 2001, which has resulted in increased instructional time in tested subjects and test-focused school leaders who neglect school climate factors which have been associated with positive student development and increased student achievement. The theoretical framework of resilience, applied to the school setting, along with associated school climate data, may offer keys to improved school organization, instructional delivery, data analysis, and teacher training, resulting in improved student outcomes. The California Healthy Kids Survey (CHKS) and its Resilience Youth Development Module (RYDM) represent a research-based, psychometrically-sound instrument that measures school climate elements, such as external school protective factors, internal student assets, and school connectedness. The independent variables of this study included external school protective factors, such as: caring adults, high expectations, and opportunities for meaningful participation; internal student assets, such as: problem-solving, self-efficacy, empathy, and self-awareness; demographic control variables, such as percent number of students: African-American, Hispanic/Latino, participating in free/reduced meals, and English language learners; and a school connectedness variable. Aggregated school-level scores were drawn from 1.5 million student cases (n = 1143, 987, and 836 schools in 2004, 2006, and 2008, respectively). The dependent variables were school Academic Performance Index (API) scores. This study investigated the relationship between select CHKS items and subscales to a student achievement measure; school API score, a figure calculated by California Department of Education's general accountability system based on standardized test performance. This correlational study with replicated procedures across three sets of data examined matching 7th grade CHKS data and school API scores through descriptive and inferential statistical analyses in school years 2003-2004, 2005- 2006, and 2007-2008. A three-part statistical procedure for data analysis included a zero-ordered simple correlation to school API, then two forced-entry hierarchical multiple regression analyses that accounted for the effects of all variables, and the tested effect of the mediator variable, school connectedness. Study findings indicated that the school meaningful participation and school connectedness variables demonstrated statistically significant positive correlations to school API scores through three study replications, after accounting for the effect of all other study variables, such that the higher the reports of school meaningful participation and school connectedness, the higher the school API score. School connectedness, however, was three to four times a more powerful predictor of school API scores than school meaningful participation. The study findings support educational leadership approaches and policy development efforts that purposefully bolster school connectedness and school meaningful participation to more positively impact student learning and school reform efforts.