Background <p>Universal, systematic psychosocial screening in childhood cancer assures care matched to need and achieves a Standard of Psychosocial Care. It is accomplished inconsistently due to barriers at the family, provider, and institution level, potentially contributing to disparities in care and outcomes. We conducted a comparative effectiveness trial of two implementation strategies of an established measure (Psychosocial Assessment Tool; PAT3.0) across 18 children’s cancer programs to identify strategies that resulted in higher levels of screening in English and Spanish (penetration, health equity). We also examined uptake at the institution level (adoption).</p> Methods <p>Sites were randomized to Strategy I (web-based training curriculum [WebTC] + a written, site-specific Implementation Plan) or Strategy II (Strategy I + Consultation Calls + a Champion) and to one of three year-long cohorts. Randomization was stratified by site size (new patients/year (small [&lt; 50], medium [50–149], large [&gt; 150]). Sites provided data to a central data coordinating site, including eligible and screened patients/families and type of insurance as a proxy for socioeconomic status (SES). ANOVAs compared percentage of eligible patients/families screened, eligible Hispanic patients/families screened, patients/families screened by identified race, patients/families screened by SES, and feedback provided to families across Strategy. Data from a WebTC feedback form and the sites’ PAT implementation plans were summarized.</p> Results <p>There were no differences between Strategy I and II in percentage of patients/families screened for 1) all eligible families; 2) Hispanic families; 3) identified race; 4) SES; and 5) feedback provided. Exploratory analyses examining strategy by size by cohort, identified lower percentages of patients/families screened in the second cohort. The WebTC was rated as clear and helpful in understanding the importance of screening and how to screen as part of workflow. On the PAT Implementation Plan, most sites screened a subsample of their cancer program population (e.g., inpatients, hematologic malignancies) with social workers or psychologists as screeners.</p> Conclusions <p>Comprehensive web-based training + Implementation Plan supported implementation of an established psychosocial screener, inclusive of racial and ethnic minoritized, English and Spanish-speaking, and lower SES patients/families. Implementation planning to address barriers at the patient, providers, and institution levels is indicated for successful screening of all patients and as part of childhood cancer program efforts to meet the Psychosocial Standards.</p> Trial registration <p>ClinicalTrials.gov, NCT04446728, registered 23 June 2020. <a href="https://clinicaltrials.gov/study/NCT04446728">https://clinicaltrials.gov/study/NCT04446728</a>.</p>