Roughly half of all undergraduate students in the United States fail to persist to degree completion (American College Testing [ACT], 2010; Tinto, 1993; U.S. Department of Education, National Center for Education Statistics, 2013). Adult students often have higher levels of attrition than traditional-age students (Justice & Dornan, 2001; Noel-Levitz, 2011). This study uses theoretical underpinnings from Bean and Metzner (1985) and Braxton, Hirschy, and McClendon (2004) to develop and apply a conceptual model of adult student persistence. We explore the effects of (1) student entry characteristics, (2) external (i.e., extra-institutional) environments, and (3) campus environments on adult students' persistence. The context is a research-intensive, public, urban institution in the United States. We find that educational aspirations, institutional responsiveness, and familial encouragement play significant and positive roles in helping adult students remain enrolled and graduate.