The study examined the integration of science and mathematics methods courses and preservice teachers' understanding of constructivism. The participants were 50 preservice teachers who were enrolled in early childhood education mathematics and science methods courses, and an early childhood practicum. The two methods courses were integrated and the instructors adopted a collaborative approach, including common syllabi, texts, assignments, and teaching strategies. The preservice teachers completed e-journal reflection that were subsequently coded and analyzed. The findings suggested that the instructional approach enabled students to develop and refine their understanding of constructivism. (Contains 1 footnote.)