An epistemic authority is a source of information that exerts an influence on the formation and acquisition of knowledge in the knower. The epistemic authorities used by undergraduates to construct views about two controversial science topics, evolution and global warming, were investigated at a large Southeastern public university. Four hundred and forty six questionnaires were dispersed and analyzed. Three basic positions were elucidated for evolution and for global warming after inductive thematic analysis of twenty questionnaires, comprising nine evolution/global warming positions on a three by three grid. Fourteen participants, representing all nine positions, consented to in-depth interviews about their epistemic authorities. A wide variety in both the role and characterizations of these epistemic authorities was found. Participants used a wide variety of religious, scientific, and nonspecific authorities to construct their evolution views, while they used a wide variety of media, scientific, and nonspecific authorities to construct their global warming views. Different participants used both general and specific authorities to construct their positions. Participants were also rated as possessing scientific knowledge or belief using a theoretical lens constructed for this purpose.