With the growing life expectancy for individuals with intellectual and developmental disabilities, siblings will increasingly assume responsibility for the care of their brother or sister with intellectual and developmental disabilities. Using a 163-item survey completed by 757 siblings, the authors identified factors related to future caregiving expectations. Siblings expected to assume greater caregiving responsibility for their brother or sister with disabilities if they were female, had closer relationships with and lived closer to their brother or sister with intellectual and developmental disabilities, and were the lone sibling without a disability. Siblings who expected to assume higher levels of caregiving had parents who were currently more able to care for their brother or sister with disabilities. With a better understanding of who intends to fulfill future caregiving roles, support can be provided to these siblings.