This study provides insight into the effectiveness of Supplemental Instruction (SI) at a Hispanic-serving institution (HSI), particularly with Hispanic students. The United States Department of Education (2010) defines an HSI as having a 25% or greater full-time, Hispanic student enrollment and 50% or more of all students are eligible for need-based financial aid. It is essential for many Hispanic-serving institutions (HSIs) that have a high percentage of Hispanic populations to find ways where they will support and retain a growing number of minority degree-seeking students. One of the biggest challenges for HSIs is not only increasing retention, but additionally supporting the Science, Technology, Engineering, and Math (STEM) courses at these institutions. The study contributes to the existing research that shows that SI is an effective student success intervention in improving academic success and course retention among Hispanic students in STEM related courses. The results showed a significant difference in academic success and course completion among Hispanic students at an HSI with SI participation in Chemistry and Physics courses.