ABSTRACT. Comprehension in the 21st century substantially benefits from attending to, thinking about, and positioning the sources of any presented information. Doing so requires mental effort, and unfortunately people do not always engage in such activities. In this talk I describe a nascent, evolving model of discourse comprehension that formalizes mechanisms to predict and explain people’s strategic use of source information. The discrepancy-induced source comprehension (D-ISC) model and its assumptions help explicate the moment-by-moment cognitive processes readers engage in when they interact with potentially contradictory or controversial messages presented by varied information sources. The utility of the model is supported by evidence from a growing research base examining single and multiple text comprehension experiences. The model is also useful for suggesting future directions by way of testable hypotheses that could help build more nuanced understandings with respect to people’s understandings of materials presented from diverse sources and outlets.