The ways that humans acquire information is undergoing a fundamental change comparable to the introduction of Gutenberg's printing press and broadcast systems. Using the literature and a growing body of empirical evidence, we describe a model of information acquisition that specifies the roles of education, salience, subject-matter literacy, and navigation skills in the decision to seek information. We refer to this model as a just-in-time information acquisition system. We focus on the acquisition of health information and science information separately and discuss the similarities and differences. We utilize a national U.S. survey to describe adult information acquisition behaviors empirically.