Meiosis is a biological concept that is both complex and important for students to learn. This study aims to explore first-year biology students' explanations of the process of meiosis, using an explicit theoretical framework provided by the Structure of the Observed Learning Outcome (SOLO) model. The research was based on responses of 334 first-year biology students to practical and examination questions about meiosis, together with student interviews. Students' written responses were coded, which resulted in a hierarchy of qualitatively different categories consistent with recent developments in the SOLO model. Most responses described a number of the less abstract elements of meiosis, but not in a coherent, relational manner, and interviews elucidated several areas of confusion about meiosis and its subordinate concepts. These findings are consistent with much previous research, and provide insights into both the use of the SOLO model as a research tool and students' understandings of meiosis. In conjunction with previous research, the results of this study raise questions beyond its local context about the match between students' apparent understandings and university expectations. The implications of the study relate to the use of terminology, the treatment of meiosis in textbooks, and some specific issues of pedagogy. (Contains 2 tables and 1 figure.)