Science is of critical importance to daily life in a knowledge society and has a significant influence on many everyday decisions. As scientific problems increase in their number and complexity, so do the challenges facing the public in understanding these issues. Our objective is to focus on 3 of those challenges: the challenge of reasoning about knowledge and the processes of knowing, the challenge of overcoming biases in that reasoning, and the challenge of overcoming misconceptions. We propose that research in epistemic cognition, motivated reasoning, and conceptual change can help to identify, understand, and address these obstacles for public understanding of science. We explain the contributions of each of these areas in providing insights into the public's understandings and misunderstandings about knowledge, the nature of science, and the content of science. We close with educational recommendations for promoting scientific literacy.