This article examines the expansion of public Montessori education and its implications for student participation and outcomes. The study focuses on the state of South Carolina, which has the largest number of public Montessori programs in the United States. Through a comprehensive analysis of demographic characteristics and standardized test scores, we investigate the participation of different student groups in public Montessori programs and compare the academic achievement of public Montessori students to their peers in traditional public schools. The findings indicate that public Montessori attracts a diverse range of students, but there is an underrepresentation of less-resourced students and students of color in public Montessori programs. Using matching procedures, we find that Montessori students demonstrated higher achievement growth in ELA and math compared to similar traditional public school students. Subgroup analyses find that higher achievement growth for Montessori students is consistent across many student groups. This study provides a comprehensive analysis of public Montessori and highlights the importance of considering curriculum and educational philosophy when evaluating the impact of education policies and programs.