A key process in sentence comprehension is the identification of thematic roles. This is often impaired in aphasia, which is referred to as a-syntactic comprehension. Based on the Competition Model by Bates and MacWhinney, this study investigated how different semantic, syntactic, and morphological information (cues) in the German language affects sentence comprehension in individuals with aphasia. To this end, two empirical studies were conducted with aphasia patients and two equally sized control groups. Both group analyses and single-case analyses were performed and presented in the study. In the discussion, an extension of the Competition Model was proposed, whereby its architecture was supplemented on one hand by models of working memory, and on the other hand by the assumption of a second processing route based on heuristics.