This chapter analyzes the design, implementation, and impact of playgrounds that foster inclusion for young children with developmental disabilities. It highlights the rising prevalence of these disabilities in the U.S. and the importance of social participation—engagement with environment and peers—for children’s well-being. Differentiating accessible, inclusive, and universal playgrounds, the chapter emphasizes that universal playgrounds, based on Universal Design principles, best serve children and caregivers of all abilities with equitable, engaging, and developmentally appropriate play. Using evidence-based design and stakeholder feedback, a case study of a universally designed playground shows high utilization across ages, with over 80% of the facility accessible. Survey and observational data reveal positive experiences for children, grandparents, and caregivers, including shared play and increased engagement. While barriers to social play persist, universal playgrounds help overcome exclusion, supporting social integration for children with disabilities. The chapter advocates for data-driven evaluation and inclusive playground design to fulfill the rights and needs of diverse families.