This paper describes and discusses the effect of service-learning on students' reflective thinking about their own knowledge in multicultural teacher education at a state university in Southern California (USA). Two versions of students' multicultural autobiographies, one at the beginning and the other at the end of the course, were examined to determine their individual progress. Two classes, one with a service-learning assignment and the other without, were involved to identify differences. Using King and Kitchener's model of reflective judgment, this study compares and contrasts the progress of student critical reflective thinking and differences between the two classes. The research suggests that service-learning stimulated and increased students' reflective thinking about their own knowledge in multicultural education.