OBJECTIVE: The COVID-19 pandemic has severely impacted children's mental health. All children have not been affected equally, however, and whether parental emotion socialization might buffer or exacerbate the impact of COVID-19 on children's mental health remains an important question. METHOD: During the first peak of the COVID-19 pandemic in the U.S. N = 200 parents of children ages 0-17 (52.5% female) completed questionnaires related to parental assistance with children's emotion regulation, symptomatology, and exposure to COVID-19-related stress. Parents were 74% Non-Hispanic/Latino/a White, 13% Asian, 4.5% Hispanic/Latino/a, 4% Black/African American, 2.5% Native American, and 1.5% bi/multiracial; 0.5% of participants preferred not to state their race/ethnicity. In a series of linear regression analyses, we examined whether parental assistance with children's execution of emotion regulation strategies - across a variety of prototypically-adaptive and -maladaptive strategies - moderates the association between children's exposure to COVID-19-related stress and symptomatology. RESULTS: Results suggest that parental assistance with the execution of prototypically-adaptive strategies (i.e., acceptance, problem solving, behavioral disengagement) and prototypically-maladaptive strategies (i.e., suppression, rumination) may buffer or exacerbate, respectively, the impact of COVID-19-related stress on youth mental health. CONCLUSIONS: Though interpretation of findings is constrained by limitations inherent in collecting data during a pandemic, results highlight the importance of supporting parents - who play a critical role of supporting children - during public health emergencies that affect family life. Interventions designed to improve child wellbeing during the ongoing pandemic may benefit from training parents to assist their children with specific emotion regulation strategies.