To adults entering a Montessori classroom for the first time, the activities they observe may not seem particularly academic. Depending on the students' ages, children might be found working independently, having spirited discussions in small groups, or working on long-term projects. Inconspicuous teachers observe and take notes or give lessons to small groups. Especially if habituated to classrooms that are teacher led and dominated by whole-group instruction, observers mightnot notice that learningis happening through a different route. Inthis method, learning activities are self-determined, initiated, and controlled by students according to their own wishes. As we describe below, learning in the Montessori system hinges on students' self-determined engagement. Students are given opportunities and encouragement to exercise choice in several aspects of their learning; indeed, psychology research indicates that such engagement is good for students' learning and well-being (Gottfried 1986; Hardre and Reeve 2003; Lepper et al. 2005). We explain how environmental conditions that can enhance engagement are encoded in Montessori classrooms. Finally, we review research on motivational and educational outcomes from Montessori education and conclude with questions for future research. [This a chapter in: Angela K. Murray, Eva-Maria Tebano Ahlquist, Maria K. McKenna and Mira Debs (Eds.), "Bloomsbury Handbook of Montessori Education," 261-270, Bloomsbury Publishing (2023).]