The first experiment tested four groups in identifying the appropriateness of a stimulus. Group 1 consisted of 10 sex offenders; Group 2, of 10 inmates serving sentences for crimes other than sexual offenses; Group 3, of 20 nonoffender males; and Group 4, of 10 nonoffender males given an alcoholic beverage prior to testing. The stimuli consisted of two sets of six taped descriptions of sexual interactions between adult males and females: the first three episodes were mutually consenting, and the last three contained rape cues. The subjects were told to press a button to signal something inappropriate or wrong. Rapists responded like normals and nonrapist inmates on Tapes 4 and 5; however, on Tape 6, in which the male physically assaults and rapes the female, the rapists identified inappropriate cues later than did all the other groups. The drinkers responded consistently earlier than the other groups. The second experiment assessed penile erection in a group of 10 sex offenders and in a control group of 10 normal men. Tapes 1, 2, and 5 from the first experiment were shown. The mean rape indices produced by rapists during baseline measures was .89, as compared to .46 for normals; the group of rapists in this study were found to have similar erectile preferences to those in earlier research. The authors conclude that rapists are able to control arousal to inappropriate cues and can identify them quite readily. The difference between laboratory and real world-control behavior is suggested for additional study. Eighteen references and two figures are provided.