In undergraduate STEM settings, students' beliefs about their intellectual abilities (lay theories) affect their academic and psychosocial outcomes and their overall learning experiences. These lay theories consist of three distinct beliefs: mindset (extent to which intelligence can improve), brilliance (whether a high level of ability is required for success), and universality (distribution of potential for high intelligence). Previously, five factors have been identified that inform students' mindset beliefs: academic experiences, observing peers, deducing logically, taking social cues, and formal learning. Alas, less is known about the factors that shape students' brilliance and universality beliefs. Our study aims to address this gap. We interviewed 19 organic chemistry students at a private university on the West Coast. We asked students to explain their mindset, brilliance, and universality beliefs, and then describe the factors that informed their beliefs. Our initial findings reveal themes consistent with three of Bandura's (1977) sources of self-efficacy: enactive mastery experiences (prior academic outcomes), vicarious experiences (observations of others' experiences), and verbal persuasions (statements from others). This suggests that the self-efficacy framework may be more broadly applicable than once thought. We identified two themes that align with Limeri and colleagues' (2020) findings: logical deductions and formal learning. We also identified novel themes, including feedback from a course instructor and university resources (i.e., access to support from the institution, e.g., supplemental instructors, faculty office hours), which demonstrate how instructors can leverage pedagogical decisions to help students develop productive lay theories. With the data we continue to gather, we can help make specific and practical recommendations to educators and institutions about how we can enhance student learning by cultivating productive lay theories.