Employment, social relationships, and autonomy are priorities to people with intellectual and developmental disabilities (IDDs). However, few validated measures exist to systematically assess these key adult outcomes in this population. This research includes first steps to develop self- and proxy report measures of life outcomes for adults with IDDs--the Relationships, Employment, Autonomy, and Life Satisfaction (REALS). A literature search identified existing adult outcome measures, and comparison of their domains informed initial conceptual model development. External consultants revised the model, and items were generated. Autistic adults (n = 15), adults with other IDDs (n = 7), caregivers of autistic adults (n = 13), and caregivers of adults with other IDDs (n = 10) completed in-depth cognitive interviews to assess comprehension of items and response categories, factors influencing how participants respond to items, and the inclusiveness of the item pool. A final conceptual model was generated with three subdomains (social relationships, employment, and autonomy), including assessment of life satisfaction within each domain. Cognitive interviews revealed that response set restructuring and item-level revisions were needed to capture the complexity of adult life and make the measure more accessible across a range of abilities. This study developed a conceptual model of relationships, work, and autonomy specific to adults with IDDs. Future work will involve collecting data from 800 + self-reporters with IDDs and 800 + caregivers of adults with IDDs to conduct psychometric analyses. Improving measurement in this area is critical to better understanding the needs of adults with IDDs and improving services available to them.