Objective: To develop a system to guide interpretation of scores generated from the newly developed item response theory (IRT)-based Functional Assessment in Acute Care Multidimensional Computerized Adaptive Test (FAMCAT), which assesses 3 important domains of function: Mobility, Daily Activities, and Applied Cognition. Design: Cross-sectional data was used to inform a modified Delphi approach to establish FAMCAT cutpoints delineating various functional ability levels. Setting: Large midwestern academic teaching hospital. Participants: Patients hospitalized to an inpatient medical service (N=2049). Interventions: Not applicable. Main Outcome Measures: FAMCAT Basic Mobility, Daily Activity, and Applied Cognition scores. Results: IRT-based score estimation data was successfully integrated with expert clinical feedback using a modified Delphi process to arrive at consensus yielding 4 functional level strata (ranging from bed-based mobility to independent mobility) for both the FAMCAT Mobility and Daily Activity scales; 1 cutpoint was supported to delineate 2 functional strata for Applied Cognition. Conclusions: Meaningful cutpoints were established for each FAMCAT domain using a data-informed, modified Delphi process for achieving consensus. The resulting FAMCAT interpretation guide may be used to develop an ability-matched mobility preservation program and identify patients who may require a higher level of supervision based on the resulting FAMCAT scores.