Objective: To compare problem-solving skills and everyday competency across clinical groups. Design: Between-groups design. Setting: Acute neurosurgery unit, community for the elderly, assisted living facilities for elderly and people diagnosed with schizophrenia, and nursing homes for the elderly. Participants: 60 older adults (age, ≥65y), 40 adults diagnosed with schizophrenia, and 40 adults with brain injuries. Interventions: Not applicable. Main Outcome Measures: Everyday competency was assessed using the Revised Observed Tasks of Daily Living (OTDL-R). Results: OTDL-R performance was significantly worse for participants diagnosed with schizophrenia than for participants with brain injury or older adults. Performance of the latter 2 groups did not differ. Higher educated persons in each of the 3 groups performed at a significantly higher level than less educated persons. Furthermore, older persons in each group performed worse than younger persons. Conclusions: The OTDL-R is a sensitive performance-based tool of potential importance for occupational therapists in the assessment of instrumental activities of daily living and problem-solving skills. However, education level and age should be taken into consideration during assessment. Additional research is needed to characterize more fully the psychometric properties of the OTDL-R for appropriate use by clinicians and researchers.