The aim of our two experiments was to verify the efficacy of a semantic tracking task (Quinsey&Chaplin, 1988a) in reducing the magnitude of voluntary control homosexual pedophiles exert on their penile responses. In Experiment 1, the penile responses of homosexual pedophiles unfamiliar with phallometric testing were recorded, using a mercury in rubber strain gauge during the presentation of pedophilic and nonpedophilic sexual stimuli. The results showed that the mean pedophilic index of those assessed while carrying out a semantic tracking task did not differ from the mean index obtained with those assessed without performing that task. In Experiment 2, the same stimuli and assessment procedures were used with homosexual pedophiles who were familiar with phallometric testing. The mean pedophilic index obtained in the session in which the pedophiles were carrying out the semantic tracking task was higher and more consistent with their pedophilic behavior than the mean pedophilic index obtained in the session in which they were assessed without performing that task. We therefore concluded that the use of a semantic tracking task increased the internal validity of phallometry in homosexual pedophiles, especially among those with prior experience in phallometry.