The Early College High School (ECHS) initiative developed in response to calls to significantly decrease the number of first-generation college and underserved students of color and from poverty who are high school dropouts or marginally graduates (i.e., ill prepared for college). The ECHS model is different from other educational reforms in that secondary and postsecondary faculty work collaboratively to align curriculum and supports that facilitate a successful high school-to-college transition. The purpose of this study was to evaluate the effects of the initial implementation of ECHS on student achievement and nonacademic indicators in a high-poverty setting. Results indicated that, after an initial year of implementation, achievement results on criterion-referenced tests were significantly higher for all students relative to matched control students, but the statistically and practically significant impact on norm-referenced tests was limited to students enrolled in ECHS courses; school attendance remained the same, but suspensions were decreased. Implications for high school reform and research are discussed.