Background: Friendship is important to quality of life, yet people with intellectual disability have more restricted social networks and fewer friends outside family and support staff. Method: Data from a nationally representative longitudinal study of older adults with intellectual disability (aged >40) examined rates and types of friends. Factors associated with having a best friend and friendship quality were explored. Results: A large majority (92.4%) had friends but just over half (52%) had a best friend. Co-resident friends (71.8%) were more common than non-resident friends (62%), while staff friendships (62.5%) were important. The majority of best friends were peers with intellectual disability (63.2%), carer/service providers (15.9%) or family (8.4%). Challenging behaviour and communication difficulty were associated with reduced likelihood of having a best friend. A best friend with intellectual disability was associated with lower friendship quality scores. Conclusion: Limited choice and social opportunity may result in a precarious form of friendship for older people with intellectual disability that undermines their quality of life.