Siblings of individuals with intellectual and developmental disabilities (IDD) are frequently involved in their brother’s or sister’s life longer than anyone else in their family. They have unique experiences, perspectives, and needs that are too important to ignore, and yet they often feel overlooked as service providers, educators, family members, and others focus primarily on the needs of the sibling with disabilities and parents. In this Impact issue we focus on the brothers and sisters of children, teens, and adults with IDD – what we know about them, their roles and needs across the lifespan, their feelings about themselves and their siblings, and how to support them. We share their personal stories, profile organizations around the world that are giving them a place to connect with one another, offer strategies and resources for addressing their concerns, and describe some of the research available about them. Our hope is that in reading this issue siblings will have moments when they say, “Yes, that’s my experience too!” and know they are not alone, and that those around them will have an increased understanding of how to support the sibling role.