The purpose of this investigation was to explore students' epistemic beliefs and conceptual understanding of biotechnology. Epistemic beliefs can influence reasoning, how individuals evaluate information, and informed decision making abilities. These skills are important for an informed citizenry that will participate in debates regarding areas in science such as biotechnology. We report on an in-depth case study analysis of three undergraduate, non-science majors in a biotechnology course designed for non-biochemistry majors. We selected participants who performed above average and below average on the first in-class exam. Data from multiple sources--interviews, exams, and a concept instrument--were used to construct (a) individual profiles and (b) a cross-case analysis of our participants' conceptual development and epistemic beliefs from two different theoretical perspectives--Women's Ways of Knowing and the Reflective Judgment Model. Two independent trained researchers coded all case records independently for both theoretical perspectives, with resultant initial Cohen's kappa values above 0.715 (substantial agreement), and then reached consensus on the codes. Results indicate that a student with more sophisticated epistemology demonstrated greater conceptual understandings at the end of the course than a student with less sophisticated epistemology, even though the latter performed higher initially. Also a student with a less sophisticated epistemology and low initial conceptual performance does not demonstrate gains in their overall conceptual understanding. Results suggest the need for instructional interventions fostering epistemological development of learners in order to facilitate their conceptual growth.