In recent years, biodiversity has received a great deal of attention worldwide, especially in environmental education. The reasons for this attention are the increase of human activities on biodiversity and environmental problems. The purpose of this study is to investigate biology student teachers' conceptual frameworks regarding biodiversity. Data are collected from 130 participating students using a free word association test. An analysis of the free association test illustrates the conceptual frameworks of participants, regarding the biodiversity issue with its various aspects. Although participants know the term "biodiversity," they are not fully aware of the comprehensive concepts included in the term, particularly the sustainable use of biodiversity. The participants think ecosystem and species diversity rather than genetic diversity in the context of biodiversity components. Effects of human activities on biodiversity loss are also not represented strongly in the categories. These results are compared with related literature and recommendations are provided. (Contains 1 table.)