This longitudinal quantitative study determined the impact of a summer mathematics academy for early learners on their number sense and how their number sense compared to that of their peers who did not attend the academy. The Texas Early Mathematics Inventory -- Progress Monitoring (TEMI-PM) was used to measure students' number sense. Results revealed that (1) all participants showed growth in their understanding of Number Identification in their first year of attending the academy, (2) participants who attended for two consecutive years grew in multiple areas of early number sense, and (3) participants who attended for one year demonstrated a decreased gap when compared to peers. The evidence supports the benefits of a mathematics-focused summer intervention to develop number sense for early learners.