The performance of normal and aphasie subjects on a sentence-picture matching task shows that many different factors can affect accuracy. The data presented in this paper suggest that, for normal subjects, reversal errors are not errors of sentence parsing or comprehension, but reflect "late" stages of processing which mediate the translation between language and pictures. We argue that normal performance is significantly affected by the semantic or conceptual properties of the verbs used and by the interaction of verb meaning and sentence meaning. Aphasie errors, on the other hand, can arise from different sources and have multiple causes. We discuss data from three aphasic subjects who appear to have similar linguistic symptoms, and we argue that each patient fails on this task for different reasons.