Leading national health organizations have declared pediatric mental health an urgent public health issue. Pediatric primary care is an ideal setting to improve mental health in young children; however, various existing barriers limit the effective identification of social-emotional risk among toddlers. This special section of Families, Systems, & Health includes four articles that identify multilevel barriers and facilitators to population-level early childhood mental health screening, identification, and referral and describe implementation strategies that may be used to improve pediatric mental health. In the first article, authors describe clinicians' concerns regarding the social-emotional screening of young children. In the second article, authors highlight the potential for a transdiagnostic screening tool for assessing toddler irritability that may support clinical decision making. In the third article, authors use information gathered from clinicians to generate a logic model that can guide the implementation of screening and referral for toddlers with elevated social-emotional risk. In the fourth article, authors explore caregivers' perceptions of other factors, such as effectiveness, demand, and cost, of the proposed intervention, that may impact their service engagement. Together, these articles outline a plan for facilitating early childhood mental health screening, identification, and referral that has the potential for reducing the prevalence of pediatric mental health diagnoses. (PsycInfo Database Record (c) 2024 APA, all rights reserved).