Personal epistemology, which refers to individuals’ beliefs about knowledge, is an important component for promoting deeper learning and engagement and higher-level critical thinking. We examined developmental, cultural, contextual, and gender differences in personal epistemology among 240 fourth-grade and sixth-grade students in six different countries. Students were asked to list entities that looked like knowledge to them, at school and at home, and provide a rationale for why they thought the entity looked like knowledge. A number of themes emerged from students’ rationales that demonstrate epistemological beliefs regarding sources of knowledge, certainty of knowledge, and connections among knowledge, learning, and intelligence. Additionally, some new themes emerged that have previously not been discussed in the personal epistemology literature, including aesthetics, feelings, and sustainability. Developmental, cultural, contextual, and gender differences are discussed.