This paper examines how three preservice teachers, who previously worked in science-related fields, confronted barriers in the process of becoming science teachers. Many of the barriers these teachers faced were similar to the barriers that more traditional teacher education candidates faced, but they also faced some barriers that were less common for traditional preservice teachers. Specific barriers explored include contextual issues related to family, finance, employment, and time; institutional concerns as in returning to school as an undergraduate; vocational concerns related to shifting views of profession and identity; and intellectual barriers such as the misfit of science discipline areas to school science. The three case studies presented in this paper demonstrate how barriers overlap and interact in a wide variety of ways to influence experiences in a teacher education program on into the beginning year of a new career. (DDR)