This brief introduces the Global Research Agenda for Children with Disabilities that sets out critical challenges: widespread data gaps, research underfunding, and limited visibility of children with disabilities in research. It sets out not only what needs to be studied, but how--emphasising ethical, participatory approaches and cross-cutting priorities such as intersectionality, climate risk, and the leadership of organisations of persons with disabilities. Grounded in the lived experiences of children and youth with disabilities, the Research Agenda offers governments, donors, and researchers a practical tool for investing in what works--where it matters most. The Research Agenda directs attention to the areas where evidence is weakest, needs are greatest, and the potential for real-world impact is highest.