This report is a longitudinal examination of "Preschool for All" (PFA) participants, tracking students' experiences across their first four years in elementary school. It builds upon a 2009 study that found that PFA graduates in San Mateo County were better prepared for kindergarten than their classmates who had not attended preschool and equally ready for kindergarten as classmates with other preschool experiences. To conduct the analysis, researchers used the Youth Data Archive to link individual student records from three PFA cohorts to their Redwood City School District records. The analysis suggests that participating in a high-quality preschool program was associated with positive academic outcomes for children once they entered the K-12 school system. It is important to note that PFA served children who might not otherwise attend a high-quality preschool program, targeting those in traditionally underserved groups. These children might not be expected to perform similarly given the documented disparities in achievement between at-risk students and their peers that persist throughout the elementary grades. The fact that PFA participants were just as likely to be persistently proficient in some subjects as students who did not participate in PFA is noteworthy; in particular, because these longitudinal comparisons used students' raw proficiency scores, unadjusted for demographics, and because students who did not attend PFA likely participated in other preschool programs.