This study examined the views, and the retention of these views, of 19 preservice elementary teachers as they learned about nature of science (NOS). The preservice teachers participated in a cohort group as they took a science methods course during which they received explicit reflective instruction in nature of science. Through Views of Nature of Science version B (VNOS-B) surveys and interviews it was found that most preservice teachers held inadequate ideas of nature of science prior to instruction, but improved their views after one semester of instruction in the science methods course. However, 5 months after instruction, the graduate preservice teachers were again interviewed and it was found that several of the students reverted back to their earlier views. The results are interpreted through Perry's scheme, and implications and recommendations for elementary science teacher education are made.