This study used covariate adjusted regression techniques to compare the third-grade outcomes of low-income Latinx children who attended Montessori pre-K programs (n = 161) with those who graduated from more conventional programs (n = 4975) in Miami-Dade County, Florida. Children who experienced one year of Montessori education demonstrated stronger pre-academic skills at the end of pre-K and, in turn, performed better on standardized assessments of math and reading in third grade than those who did not. No differences emerged in students’ identification as gifted and talented nor in third-grade GPA. Taken together, these findings suggest that the benefits of one year of Montessori at age 4 may carry forward over time and to the extent that they do, these benefits are attributed to the fact that Montessori graduates entered kindergarten more ready academically. At the same time, however, the persisting benefits of Montessori were 60–70% smaller four years after program exit and were less robust than the end of pre-K outcomes. (author abstract)