The purposes of this study are to explore fifth graders' epistemological views regarding their own experiences of constructing scientific knowledge through inquiry activities (i.e., practical epistemologies) and to investigate possible interactions between students' practical epistemologies and their inquiry skills to construct scientific explanations (i.e., explanation skills). Quantitative and qualitative data including interview transcripts, classroom video recordings, and pre- and post-tests of explanation skills were collected from 68 fifth graders in two science classes. Analyses of data show that after engaging in 5-week inquiry activities, students developed better inquiry skills to construct scientific explanations. More students realized the existence of experimental errors, viewed experimental data as evidence to support their claims, and had richer understanding about the nature of scientific questions. However, most students' epistemological beliefs were still naive (the beginning level); they could not differentiate between experimental results and scientific knowledge and believed that the purpose of science is doing experiments or research. The results also show that students who held a more sophisticated epistemology (the intermediate level) tended to develop better inquiry skills than those with naive beliefs. Analyses of classroom observations suggest possible explanations for how students reflected their epistemological views in their inquiry practices.