Background: Despite growing recognition of their right for inclusion in society, people with intellectual disabilities are often excluded from mainstream services, or experience poor service outcomes. Method: Taking a relational approach that considers the interpersonal relations and interactions that occur in mainstream service settings in Australia, this paper examines the features of services that research participants considered more inclusive. Results: Relations between service users with and without intellectual disabilities, mainstream service staff and disability support workers in inclusive mainstream services were characterised by; respect; warm, welcoming and convivial interpersonal engagement; active listening; proactive assistance; flexibility; mediation to create a safe environment; and collaboration and shared responsibility by both mainstream staff and disability support workers in supporting a service user with intellectual disability. Conclusions: Building on these results, we put forward a set of principles for facilitating inclusion of people with intellectual disabilities in mainstream services.