The American Academy of Pediatrics recommends screening all children for autism spectrum disorder (ASD) at 18 and 24 months because research indicates that earlier intervention maximizes children's outcomes. The earliest signs of ASD are delays in social communication milestones that appear in the first 2 years and yet most children are not diagnosed until 4-5 years of age. Underserved families are identified even later and significantly underrepresented in intervention research. It is vitally important to mobilize community service systems to impact family engagement throughout the process of screening, evaluation, and early intervention (EI) and to support linkages to public community-based EI in order to address health disparities. This collaborative investigation of 4 universities aims to document the effectiveness of an online automated universal screen for communication delay and autism initially at 18 months of age and decision rule for referral to an ASD evaluation, and to study an evidence-based intervention to increase family engagement and expedite receipt of screening, diagnosis, eligibility for EI, and EI services. The study will focus on the youngest age when ASD can be detected reliably, which is 18 months, and compare the effectiveness of screening and referral by 3 different community service systems: 1) primary care including private and public health care agencies and federally qualified health centers; 2) federal programs such as Women, Infants, and Children (WIC) Food and Nutrition Service and Early Head Start; and 3) the National Black Church Initiative (NBCI). Using the Autism Navigator web-based platform the investigators will expand their capacity for universal ASD screening and referral for diagnosis and determining eligibility by EI providers through the public Individuals with Disabilities Education Act (IDEA) Part C system for children birth to 3 years of age. Innovative web-based technology will be integrated at multiple levels- as the basis for an interactive professional development course to enable these community service systems to efficiently learn about autism and implement a universal broadband and autism-specific screening with seamless automation that links to electronic health records and provides families with web-based tools about autism. This multidisciplinary research team will conduct a multisite pragmatic randomized clinical trial to test the effectiveness of an evidence-based Family Engagement Intervention plus Autism Navigator compared to Autism Navigator Enhanced Practice alone. The investigators will also conduct an exploratory study to test strategies to improve uptake of evidence-based intervention by community-based EI providers through the Part C system. This protocol has the potential to lower the age of screening for ASD to 18 months, which will have important implications for earlier access to intervention and improving ASD service systems and be ready for immediate and rapid implementation in community settings across the US. Findings will advance science by providing researchers with a method for recruiting a population-based sample, allowing for research at younger ages, which could accelerate genetic, neuroscience, and intervention research, and lead to transformative changes to community healthcare delivery.