Background: The functional communication deficits that result from aphasia are well known, although contributing factors have not been systematically studied. Although overall aphasia severity is directly related to communication ability, the contribution of cognitive and mood factors is less understood. Aims: This study attempted to identify predictors of functional communication in patients with acquired aphasia at various points post-unilateral left hemisphere stroke. Methods & Procedures: A total of 57 patients with aphasia due to left hemisphere stroke completed a comprehensive battery of aphasia diagnostic, neuropsychological, mood, and functional communication measures. Significant predictors of functional communication were identified with multiple hierarchical regression analysis. Outcomes & Results: Over and above the contribution of aphasia severity, depression (sadness and anger), semantic processing, and reading comprehension accounted for a significant amount of variance in functional communication. Working memory, phonologic processing, and other mood states were not predictive. Conclusions: Aphasia severity, depression, semantic impairment, and reading comprehension may be most relevant to functional communication in people with acquired aphasia.