:Objective:The purpose of this study was to assess the prevalence of child behavior, academic and sleep concerns, and parent stress and depression symptoms during COVID-19; to test associations of parent-child well-being with child school format; and to examine effect moderation by child race/ethnicity and material hardship.Methods:A total of 305 English-speaking parents of elementary school-age children completed online surveys regarding demographics, child school format, behavior, learning-related experiences, sleep, and parent stress and depression symptoms. Multivariable linear and logistic regression analyses examined associations of school format with child and parent outcomes.Results:Children were aged 5.00 to 10.99 years, with 27.8% underrepresented minority race/ethnicity. Per parental report, 27.7% attended school in-person, 12.8% hybrid, and 59.5% remote. In multivariable models, compared with children receiving in-person instruction, children receiving remote instruction exhibited more hyperactivity (β 0.94 [95% confidence interval, 0.18–1.70]), peer problems (β 0.71 [0.17–1.25]), and total behavioral difficulties (β 2.82 [1.11–4.53]); were less likely to show academic motivation (odds ratio [OR] 0.47 [0.26–0.85]) and social engagement (OR 0.13 [0.06–0.25]); were more likely to show schoolwork defiance (OR 2.91 [1.56–5.40]); and had a later sleep midpoint (β 0.37 [0.18–0.56]) and higher odds of cosleeping (OR 1.89 [1.06–3.37]). Associations of remote learning with behavior difficulties were stronger for children without material hardships.Conclusion:Children receiving remote and hybrid instruction were reported to have more difficulties compared with children receiving in-person instruction. Children with material hardships showed more behavior challenges overall but less associated with school format. Therefore, planning for a return to in-person learning should also include consideration of family supports.