The COVID-19 pandemic has interrupted the education of more than 1 billion children worldwide, with many experiencing shifts between remote, hybrid, and in-person learning. 1 As the COVID-19 pandemic and interruptions to learning continue, we need to understand their conseq u e n c e s f o r c h i l d r e n's behavioral health to inform response efforts. We used longitudinal data to examine how children's behavioral wellbeing differed by learning format.

Theoretical models assume that parental knowledge about child development and caregiving motivates parental stimulation, shaping child development. Evidence supporting these models is scarce in low‐ and middle‐income countries (LMICs). This study tests the relations between maternal knowledge, stimulation, and child development in a Colombian sample of 1,277 low‐income mothers and their children under the age of five. Mothers showed diverse knowledge about child development and caregiving. Moreover, maternal knowledge when children were 9–26 months old indirectly predicted growth in children's cognitive, receptive language, and gross motor skills at ages 27–46 months, partially through maternal engagement in stimulating activities with the child.

Highlights• Neighborhoods in nine US cities exhibit heterogeneity in socioeconomic status (SES) and resources.• Classroom instructional support is one mechanism through which neighborhoods matter for development.• Neighborhood resources matter for child development via levels of classroom quality.• Instructional quality is highest in neighborhoods with higher levels of both SES and resources.

Objective: The coronavirus disease 2019 pandemic and associated public health measures have influenced all aspects of life for children and families. In this study, we examine changes in children's behavioral health and families' well-being at the start of the pandemic. Method: We used longitudinal data on 2880 children from 1 US state collected over 3 waves to compare family and child well-being before and after a state-wide stay-at-home advisory set in March 2020. We descriptively examined levels and changes in 4 child behavioral health outcomes (externalizing, internalizing, adaptive, and dysregulated behaviors) and 4 family well-being outcomes (parental mental health, parental stress, parent-child relationship conflict, and household chaos) across the preshutdown and postshutdown periods. Fixed effects regression models were used to predict within-child and within-family differences in preshutdown and postshutdown outcomes. Results: Fixed effects analyses showed children's externalizing (0.09 points; 95% confidence interval [CI] 0.05-0.13), internalizing (0.04 points; 95% CI, 0.01-0.08), and dysregulated (0.11 points; 95% CI, 0.06-0.16) behaviors increased after the shutdown, whereas children's adaptive behaviors declined (20.10 points; 95% CI, 20.15 to 20.05). Parental mental health issues (0.22 points; 95% CI, 0.17-0.27), parental stress (0.08 points; 95% CI, 0.03-0.12), parentchild relationship conflict (0.10 points; 95% CI, 0.04-0.16), and household chaos (0.10 points; 95% CI, 0.05-0.14) all increased relative to preshutdown levels. Conclusion: Many children experienced declines in behavioral health and many families experienced declines in well-being in the early months of the public health crisis, suggesting the need for family-focused and child-focused policies to mitigate these changes.