The first task of the PROMIS network was to create a protocol for developing a domain map (framework) that portrayed the structure of each target domain and its conceptual framework or, where applicable, hierarchical structure. Existing outcome assessment questionnaires use an explicit or implicit framework that typically includes the concepts of physical function or limitation, mental health or distress, and social function, with many also including symptoms (eg, fatigue, pain). The Steering Committee (SC)-approved protocol for the domain mapping activity specified that the preliminary PROMIS framework would be developed through independent literature reviews by the Stanford PRS, the Pittsburgh PRS, and the Statistical Coordinating Center (SCC), followed by a consensus-building Delphi process and statistical analysis of available data regarding dimensionality of health status assessment. Early in the first year, the SC endorsed the World Health Organization (WHO) physical, mental, and social framework.15 Other organizing frameworks were considered, such as the WHO international classification of functioning and a 2-factor model of physical and mental health. However, after discussion and careful consideration, the SC opted to retain the WHO tripartite framework as compelling and sufficiently broad and inclusive to enable important social dimensions of health to be developed further than has been done to date. After achieving consensus on the broad WHO framework, the SC launched the Domain Mapping Protocol. Under this protocol, PROMIS network investigators used a modified Delphi approach to participate in multiple rounds of framework review and revision until consensus was reached on a detailed articulation of subordinate domains beneath the broad physical, mental, and social headings. Click here to view the Domain Hierarchy Protocol.