Students' epistemological beliefs about scientific knowledge and practice are one important influence on their approach to learning. This article explores the effects that students' inquiry during a 4-week technology-supported unit on evolution and natural selection had on their beliefs about the nature of science. Before and after the study, 8 students were interviewed using the Nature of Science interview developed by Carey and colleagues. Overall, students held a view of science as a search for right answers about the world. Yet, the inconsistency of individuals' responses undermines the assumption that students have stable, coherent epistemological frameworks. Students' expressed ideas did not change over the course of the intervention, suggesting important differences between students' talk during inquiry and their abilities to talk epistemologically about science. Combined with previous work, our findings emphasize the crucial role of an explicit epistemic discourse in developing students' epistemological understanding. © 2003 Wiley Periodicals, Inc. J Res Sci Teach 40: 369–392, 2003