Science teaching anxiety is negative emotion that inhibits a teacher's ability to start, proceed, or finish a science teaching task. Despite its detrimental effects on teachers' science teaching quality and practices, there is limited research on science teaching anxiety. To advance research in this area, there is a need for a psychometrically sound instrument assessing teachers' science teaching anxiety. This study presents the development and psychometric properties of the Science Teaching Anxiety Scale (STAS) in preservice elementary teachers (N = 191) using a Rasch analysis. In addition, it examines the relationships among science teaching anxiety, science interest, and science teaching efficacy (self-efficacy and outcome expectancy). Results indicated that the STAS has promising validity and reliability for use in future research. Moreover, science teaching anxiety and science interest were significant predictors of teaching self-efficacy in preservice elementary teachers. Implications for researchers, teacher educators, and individuals who work with new teachers are discussed.