Identity has been proposed as a mechanism to increase persistence within Science, Technology, Engineering and Mathematics (STEM) education programs. To assess the impact of identity on STEM persistence, measures that produce valid and reliable data within a given STEM discipline need to be employed. Therefore, this study developed and evaluated the functioning of science and chemistry identity measures in the context of university-level chemistry courses. The developed measures were administered to students enrolled in general and organic chemistry courses at four universities across the United States. Validity and reliability evidence for the data provided by the novel measures was supported using confirmatory factor analysis and McDonald's omega. Additionally, two competing structural equation models (SEMs), designed to explore the relations between mastery experiences, verbal persuasion, situational interest, and science or chemistry identity, were tested and compared to previously reported results. Both SEMs produced acceptable data-model fit, therefore a superior model was chosen based on theoretical support. Within both SEMs, the direct pathway (relation) between mastery experiences and identity was nonsignificant. The more supported model proposed that the relation was indirect and facilitated through verbal persuasion and situational interest. While the indirect relation was supported in both courses, the predominate pathway varied by course. Limitations of the science identity measure, recommendations for future use of the Measure of Chemistry Identity (MoChI), and suggestions for the facilitation of positive identity formation within chemistry classrooms are discussed.