This three-year longitudinal study tracked the reading performance of 68 kindergarten students from low SES backgrounds. These students received instruction with a blended learning program--Lexia® Core5® Reading--from the start of kindergarten through second grade. During each school year the students made significant gains on a standardized reading test. However, performance on the test declined significantly from the spring of one school year to the fall of the next, indicative of a substantial summer slide. Yet, further comparisons revealed that performance from the fall of one school year to the fall of the next showed significant improvement, pointing to the benefits of school-based instruction to help overcome the summer slide. More than 90% of low performers who started kindergarten scoring below average on the standardized test finished second grade scoring average or better. Benefits of Lexia Core5® Reading to support reading growth in elementary school students from low SES backgrounds are discussed.