Empathy, sympathy, and emotion regulation are core components of social-emotional development. Regulating vicariously induced negative emotions is thought to support feeling empathy and sympathy for others in need, but empirical evidence for such effects is mixed. Moreover, despite the longstanding conceptual distinction between empathy and sympathy, most researchers refer to and measure these constructs interchangeably. This meta-analysis examined associations between emotion regulation and empathy and/or sympathy in childhood and adolescence, as well as potential methodological, study, and sample moderators. Analyses were conducted on 58 studies (75 effect sizes; N = 25,831). There was a significant and positive overall association between emotion regulation and empathy/sympathy (r = .19, p < .001); however, most scales assessing empathy were conflated with other constructs. Accounting for conflation, emotion regulation was related to sympathy (r = .24, p < .001) but not empathy (r = .04, p = .38). Moreover, the association between emotion regulation and empathy/sympathy was not significant when baseline respiratory sinus arrhythmia (RSA) and RSA reactivity were examined as proxies of emotion regulation. Results were largely similar across sample characteristics (e.g., age group, sex, and culture). Conceptual implications for differentiating empathy and sympathy are discussed, as well as methodological considerations to maximize the quality and clarity of research on emotion regulation, empathy, and sympathy. (PsycInfo Database Record (c) 2024 APA, all rights reserved).