The current investigation sought to further establish the psychometric properties and ecological validity of the Multitasking in the City Test (MCT) in a clinical population. Ecological validity was addressed via correlational analyses between performance on this test and a subjective measure of everyday executive functioning (Frontal Systems Behavior Scale; FrSBe). The sample was composed of 13 individuals (11 males) who suffered a stroke or traumatic brain injury. A neuropsychological test battery consisting of the MCT and common executive and nonexecutive measures was administered. The only executive function tests that were significantly related to the FrSBe were the MCT and a semantic fluency test. Compared with a sample of normal participants, the patient group produced better plans but completed fewer tasks on the MCT. Patients made similar types of errors as normals, although some of these errors occurred more frequently in the patient sample. This study demonstrated the ecological validity of the MCT and suggested that patients can be differentiated from healthy individuals by quantitative (i.e., number of errors) rather than qualitative (i.e., type of errors) aspects of performance. Further interpretation of MCT performance and comparison with existing executive function tests is discussed.