This two-part investigation (a) assessed the impact of the Jaime Escalante Math Program (JEMP), a structured summer mathematics intervention program, on the math achievement of urban middle school students and (b) identified the characteristics of the program that the administrators and teachers perceived to contribute to student achievement. A mixed methods approach included analysis of two years of student math assessment data, administrator interviews, and teacher surveys. Quantitative findings indicate that student participants in the JEMP achieved significant growth in mathematics on two measures. Additionally, effective program elements are revealed in the qualitative data including specific classroom instructional strategies used in the JEMP. The results of this study will assist educators developing mathematics intervention programs, particularly for urban secondary students.