This study investigates how students enrolled in entry-level geology, most of whom would graduate from college without university-level physics courses, thought about and applied the concept of gravity while solving problems concerning gravity. The repercussions of students' gravity concepts are then considered in the context of non-physics courses, including implications for reform efforts in physics. Data were collected during the second week of an eleven-week term from two courses with an average enrollment of just over 100 students. Based on research literature (Claxton, 1993; diSessa, 1983; Vosniadou, 1994) and one author's experience of teaching this population of students, the authors hypothesized that students would have fragmented and loosely connected ideas about gravity. Findings, implications, and limitations of this study are discussed. (Contains 3 tables and 4 figures.)