The University of California, San Francisco's Healthy Environments and Response to Trauma in Schools (HEARTS) Program promotes school success for trauma-impacted students through a whole-school approach utilizing the response to intervention multi-tiered framework. Tier 1 involves school-wide universal supports to change school cultures into learning environments that are more safe, supportive and trauma-informed. Tier 2 involves capacity building with school staff to facilitate the incorporation of a trauma-informed lens into the development of supports for at-risk students, school-wide concerns and disciplinary procedures. Tier 3 involves intensive interventions for students suffering from the impact of trauma. Program evaluation questions were: (1) Was there an increase in school personnel's knowledge about addressing trauma and in their use of trauma-sensitive practices? (2) Was there an improvement in students' school engagement? (3) Was there a decrease in behavioral problems associated with loss of students' instructional time due to disciplinary measures taken? (4) Was there a decrease in trauma-related symptoms in students who received HEARTS therapy? Results indicate preliminary support for the effectiveness of the HEARTS program for each of the evaluation questions examined, suggesting that a whole-school, multi-tiered approach providing support at the student, school personnel and system levels can help mitigate the effects of trauma and chronic stress. Key areas for further studies include (a) an examination of data across more HEARTS schools that includes comparison control schools and (b) disaggregating disciplinary data by race and ethnicity to determine whether disproportionality in the meting out of disciplinary actions is reduced.