Affect is associated with success and persistence in STEM courses and degree programs. Measurement tools that produce valid and reliable data are essential to capturing the impact of evidenced-based instructional practices and reformed curricula on learning. We report the development of the Achievement Emotions Questionnaire for use in postsecondary organic chemistry courses (AEQ-OCHEM). Instrument development was based on the control-value theory of achievement emotions and included a revision of the seminal Achievement Emotions Questionnaire (AEQ) used to measure institutional-level learning. A thorough psychometric evaluation of the AEQ-OCHEM was conducted including alternative measurement models and an extensive investigation of the nomological framework. All AEQ-OCHEM subscales were determined to be coherent and distinct. Implications for future research using the AEQ-OCHEM are offered. A call for the development of more discipline- and course-based instruments is made. Finally, tools that measure achievement emotions in the context of instructional laboratories and undergraduate research are needed for more robust considerations of affect in STEM contexts.