Importance Concerns exist about the current quality of undergraduate medical education and its effect on students’ well-being.Objective To identify best practices for undergraduate medical education learning environment interventions that are associated with improved emotional well-being of students. Data Sources Learning environment interventions were identified by searching the biomedical electronic databases Ovid MEDLINE, EMBASE, the Cochrane Library, and ERIC from database inception dates to October 2016. Studies examined any intervention designed to promote medical students’ emotional well-being in the setting of a US academic medical school, with an outcome defined as students’ reports of well-being as assessed by surveys, semistructured interviews, or other quantitative methods. Data Extraction and Synthesis Two investigators independently reviewed abstracts and full-text articles. Data were extracted into tables to summarize results. Study quality was assessed by the Medical Education Research Study Quality Instrument (MERQSI), which has a possible range of 5 to 18; higher scores indicate higher design and methods quality and a score of 14 or higher indicates a high-quality study. Findings Twenty-eight articles including at least 8224 participants met eligibility criteria. Study designs included single-group cross-sectional or posttest only (n = 10), single-group pretest/posttest (n = 2), nonrandomized 2-group (n = 13), and randomized clinical trial (n = 3); 89.2% were conducted at a single site, and the mean MERSQI score for all studies was 10.3 (SD, 2.11; range, 5-13). Studies encompassed a variety of interventions, including those focused on pass/fail grading systems (n = 3; mean MERSQI score, 12.0), mental health programs (n = 4; mean MERSQI score, 11.9), mind-body skills programs (n = 7; mean MERSQI score, 11.3), curriculum structure (n = 3; mean MERSQI score, 9.5), multicomponent program reform (n = 5; mean MERSQI score, 9.4), wellness programs (n = 4; mean MERSQI score, 9.0), and advising/mentoring programs (n = 3; mean MERSQI score, 8.2). Conclusions and Relevance In this systematic review, limited evidence suggested that some specific learning environment interventions were associated with improved emotional well-being among medical students. However, the overall quality of the evidence was low, highlighting the need for high-quality medical education research.