Many emotion regulation assessments have been developed for research purposes, but few are frequently used in schools despite the rapid growth of social and emotional learning programs with an explicit focus on emotion regulation in schools. This systematic review provides an overview of emotion regulation assessments that have been utilized with children and adolescents of grades 1-12 or ages 6-18 in school-based research or practice within the USA over the past two decades. Qualitative analyses on the operational definition, administration and feedback, sampling characteristics, and psychometric evidence of the assessments were carried out to illuminate factors that may bridge the gap between researchers in assessment development and educators in assessment use. Emotion regulation assessments were identified via searches in educational research, psychological assessment, and social-emotional learning databases. Measure development and validation studies were then sought using academic search engines. A total of 25 assessments and 55 studies met the inclusion criteria. Results revealed divergent conceptualizations of emotion regulation, trade-offs between methodological rigor and practicality, limited transformation of raw data into actionable information, under-sampling of marginalized or disadvantaged groups, and insufficient psychometric evidence across assessments. More work is needed to enhance the scientific rigor (e.g., evidence-based recommendations and limitations for assessment use), practical relevance (e.g., sustainable use and perceived utility for students and educators), and equitable reach (e.g., accessibility and fairness for diverse student populations) of emotion regulation assessments for educational purposes.