In a democratic, industrialized society, a scientifically literate public is critical to the possibility of good policy-making. However, recent science communication has failed to generate a level of public consensus sufficient to inform rational action on important public initiatives. We propose that reorienting our epistemic goals in education, advocacy, and communication from Public Knowledge to Public Understanding might dramatically improve this situation. As it stands, however, “public understanding” is poorly understood. Social-scientific models for its promotion typically leave ‘understanding’ unexplained and fail to adequately distinguish it from knowledge. Moreover, relevant philosophical literature generally focuses on individual, rather than public understanding. Our project thus combines philosophical study of the nature of public understanding with case studies of critical science outreach efforts to: (a) develop a viable philosophical theory of public understanding alongside (b) strategic recommendations for social scientists, journalists, and policy-makers to devise better means for producing public understanding of science.