The purpose of this study was to explore science content used during college students' negotiation of biology-based socioscientific issues (SSI) and examine how it related to students' conceptual understanding and acceptance of biological evolution. The Socioscientific Issues Questionnaire (SSI-Q) was developed to measure depth of evolutionary science content use during SSI negotiation. Fifty-two upper level undergraduate biology and non-biology majors completed the SSI-Q and also the Conceptual Inventory of Natural Selection to assess evolution understanding and the Measure of Acceptance of the Theory of Evolution to appraise evolution acceptance. A multiple regression analysis tested for interaction effects between the predictor variables, evolution understanding and evolution acceptance. Results indicate that college students primarily use science concepts related to evolution to negotiate biology-based SSI including variation in a population, inheritance of traits, differential success, and change through time. The hypothesis that the extent of one's acceptance of evolution is a mitigating factor in how science content related to evolution is evoked during SSI negotiation was supported by the data, in that such content was consistently evoked by participants for each of the three SSI scenarios used in this study.