There is a need for science education research that explores community college student, instructor, and course characteristics that influence student interest and motivation to study science. Increasing student enrollment and persistence in STEM is a national concern. Nearly half of all college graduates have passed through a community college at some point in their higher education. This study at a large, ethnically diverse, suburban community college showed that student interest tends to change over the course of a semester, and these changes are related to student, instructor, and course variables. The theoretical framework for this study was based upon Adult Learning Theory and research in motivation to learn science. Adult Learning Theory relies heavily on self-directed learning and concepts of andragogy, or the art and science of teaching adults. This explanatory sequential mixed-methods case study of student course interest utilized quantitative data from 639 pre-and post-surveys and a background and personal experience questionnaire. The four factors of the survey instrument (attention, relevance, confidence, and satisfaction) were related to motivation and interest by interviewing 12 students selected through maximum variation sampling in order to reach saturation. Qualitative data were collected and categorized by these factors with extrinsic and intrinsic themes emerging from personal and educational experiences. Analysis of covariance showed student characteristics that were significant included age and whether the student already held a post-secondary degree. Significant instructor characteristics included whether the instructor taught full- or part-time, taught high school, held a doctoral degree, and had pedagogical training. Significant course characteristics included whether the biology course was a major, elective, or service course; whether the course had a library assignment; and high attrition rate. The binary logistic regression model showed six significant variables that predicted increased student interest: older students, previous degree holders, students that took courses at night rather than during the daytime, students who were taught by instructors who taught high school, instructors who taught part-time, and students who had a non-STEM major. Methodological triangulation ensured that the research questions were adequately addressed, as qualitative data corroborated and provided insights for quantitative results. These findings imply that interventions such as implementation of professional development, specifically in andragogical training for instructors and support personnel, are necessary in order to properly address the needs of community college students. Policy makers need to ensure that proper academic and financial counseling systems are in place for students enrolled in these science courses. Students were affected by past experiences and required support from others in order to increase their interest and motivation to study science. This study will inform efforts to help community college students persist in the pipeline to join in the STEM workforce or transfer to four-year colleges. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]