Most students who pursue geology degrees do so after taking an introductory course, but why are they enrolling in introductory geology courses in the first place? The development of the Beliefs of Students in Introductory Courses surveys for Geology students (Jackson & Ryker, 2019; BaSIC-Geo) began in 2019 using a qualitative-then-quantitative approach. Students enrolled in an introductory geology course were asked to share their attitudinal beliefs, subjective norms, and perceived behavioral controls around the behavior of signing up for (BaSIC-Geo I), and taking another geology course (BaSIC-Geo II) following the Theory of Planned Behavior. Responses were coded into themes, which were transformed into a series of semantic differential statements (e.g. "My advisors would ____ my decision to take this geology course..."). An exploratory factor analysis (EFA) of over 1,500 responses to the BaSIC-Geo I resulted in the creation of five subscales accounting for 41% of the variance in student responses. Key takeaways include that students signing up for introductory geology courses feel that they will enjoy and succeed in them, the content is useful to them, and that geology courses are a better option than alternatives such as physics or chemistry. In a parallel EFA assessing what would motivate students to take another course, five factors explained an initial and similar 53% of the variance in beliefs; a CFA of BaSIC-Geo II responses confirmed that all five factors remained significant. As with the BaSIC-Geo I, students are guided by the belief that geology would be better than alternatives. We also found that the approval of others, the belief that the professor cares about individual success, self-efficacy, and perceived behavioral controls were all guiding beliefs about enrolling in additional courses. This presentation includes how survey responses vary by demographic and recommendations on how to recruit students into your introductory courses.