In the United States, pediatric emergency department (ED) visits for behavioral health (BH) are increasing. We sought to determine ED-level characteristics associated with having recommended BH-related policies. We conducted a retrospective serial cross-sectional study of National Pediatric Readiness Project assessments administered to US EDs in 2013 and 2021. Changes in responses related to BH items over time were examined. Multivariable logistic regression models examined ED characteristics associated with the presence of specific BH-related policies in 2021. Of 3554 EDs that completed assessments in 2021, 73.0% had BH-related policies, 66.5% had transfer guidelines for children with BH issues, and 38.6% had access to BH resources in a disaster. Of 2570 EDs that completed assessments in both 2013 and 2021, presence of specific BH-related policies increased from 48.6% to 72.0% and presence of appropriate transfer guidelines increased from 56.2% to 64.9%. The adjusted odd ratios (aORs) of having specific BH-related policies were lower in rural (aOR 0.73; 95% confidence interval [CI] 0.57, 0.92) and remote EDs (aOR 0.65; 95% CI 0.48, 0.88) compared to urban EDs; lower among EDs with versus without trauma center designation (aOR 0.80; 95% CI 0.67, 0.95); and higher among EDs with a nurse and physician pediatric emergency care coordinator (PECC) (aOR 1.89; 95% CI 1.54, 2.33) versus those without a PECC. Although pediatric readiness for BH conditions increased from 2013 to 2021, gaps remain, particularly among rural EDs and designated trauma centers. Having nurse and physician PECCs is a modifiable strategy to increase ED pediatric readiness pertaining to BH.