In the current literature on aphasia, two explanations of paraphasic errors are suggested: one is based on the idea of conscious verbal substitutions, and the other on that of uncontrolled faults in production. The purpose of this study was to relate both explanations to a) the usual classification of verbal and phonemic paraphasias, b) the different types of aphasia, and c) the severity of the aphasic disturbance. In free reproductions of 19 fluent aphasics A(F) and 21 nonfluent aphasics A(NF), the immediate verbal context of paraphasias was examined in relation to a) the nature and severity of the paraphasic errors and b) the severity of the aphasia. The A(NF) group made significantly more hesitations before both verbal and phenemic paraphasias. There was no significant difference between the two groups in control after phonemic paraphasias, but the A(NF) showed a significantly higher rate of control incidents after verbal paraphasias. Thus the two explanations of paraphasia may correspond to different kinds of paraphasic behavior, which are symptomatic of two varieties of aphasia, fluent and nonfluent.