The purpose of this study is to identify and document student beliefs and reasoning difficulties concerning topics related to astrobiology. This was accomplished by surveying over two thousand middle school, high school, and college (science and non-science majors) students. Students were surveyed utilizing student-supplied response questions focused on the definition of life and its limitations. Careful, inductive analysis of student responses revealed that the majority of students correctly identify that liquid water is necessary for life and that life forms can exist without sunlight. However, many students incorrectly state that life cannot survive without oxygen. Furthermore, when students are asked to reason about life in extreme environments, they most often cite complex organisms (such as plants, animals, and humans) rather than the more ubiquitous microorganisms. Results of this study were used to inform the development of astrobiology curriculum materials. ©2002 Erika Offerdahl. Copyright assigned to the Association of Universities for Research in Astronomy, Inc.