As part of becoming scientifically literate, students should come to appreciate epistemic aspects of science. Little research has been conducted on elementary students' epistemological beliefs specific to science education. This study offers insights into third-grade students' epistemological beliefs while paying attention to the intersection of epistemological beliefs with instructional context. To document epistemological beliefs, students were interviewed three times during the 5-month-long study. To document instructional context, class sessions associated with two science units (16 class sessions for each unit) were video/audio-taped. Students described investigation or testing as being central to science. Although they recognized investigation as a way to get information students tended not to distinguish the tests they did from ones they envisioned scientists doing. Furthermore, students suggested that particular tests are appropriate for particular purposes, a point that was reinforced by their own investigations. These findings suggest that it is important to consider what the activities in which students are engaged in the classroom communicate about the nature of scientific knowledge. To support epistemic understandings, researchers should consider how instructional contexts capitalize on elementary students' understandings of science and push them to develop increasingly sophisticated epistemological beliefs. (Contains 3 tables.)