Dr. Angeline Lillard has a new article out in the (peer-reviewed) Journal of School Psycholoy: Preschool children’s development in classic Montessori, supplemented Montessori, and conventional programs. It is a professional journal, so they charge $35 for the full version. From the abstract:
Research on the outcomes of Montessori education is scarce and results are inconsistent. …To test whether outcomes vary according to implementation fidelity, we examined preschool children enrolled in high fidelity classic Montessori programs, lower fidelity Montessori programs that supplemented the program with conventional school activities, and, for comparison, conventional programs. … children in Classic Montessori programs … showed significantly greater school-year gains on outcome measures of executive function, reading, math, vocabulary, and social problem-solving, suggesting that high fidelity Montessori implementation is associated with better outcomes than lower fidelity Montessori programs or conventional programs.
h/t Julia Volkmann