This article describes the development and validation of an instrument called science identities, expectations of success in science, values of science, and environmental attitudes (SIEVEA). The instrument is a convenient online survey that can be used to measure students' SIEVEA. First, 1764 high school students from 11 school districts in New Jersey, Pennsylvania, and Connecticut took the SIEVEA. The collected data were analyzed using descriptive statistics and exploratory factor analysis (EFA). The EFA results provided useful insights into the factor structure of the data and led to the formation of three candidate models. All three models were evaluated based on their fit to data, their alignment with the research constructs, and their factor loadings. Because of this evaluation, the three-factor model was selected as the final model. Next, the instrument was validated through confirmatory factor analysis using a new sample data made up of responses of 1495 high school students. The developed instrument is valuable for both researchers and educators, as it allows for measurement of constructs that play an important role in successful science learning.