Three adult male sex offenders with developmental disabilities participated in an evaluation of presession factors that may influence levels of sexual arousal measured with a penile plethysmograph. We evaluated the effects of presession masturbation (1 participant) and arousal-suppression strategies (2 participants). Results showed that presession masturbation lowered arousal levels and both participants suppressed arousal to varying degrees. These outcomes suggest the potential for consideration and manipulation of presession factors as treatment components for sex offenders with developmental disabilities. (Contains 4 figures.)