The technology of penile plethysmography (PPG) for the assessment of sexual interest has been widely criticized as lacking procedural standardization and guidelines for its administration, scoring, and interpretation. In order to overcome these problems, the authors developed a stimulus set that uses VT and choice reaction time, both standardized protocols for PPG, to assess sexual interest. The use of VT to assess sexual interest is reviewed from 1942 to the present and the development of the VT stimulus set is described, which used a collection of images from the Pacific Psychological Assessment Corporation (PPAC) project. The lack of a standardized set of images made the development of a set of standardized computer-constructed or computer-modified images a top priority. Planned research on the validity and reliability of the VT assessment using adolescent and adult sex offender samples is outlined. Results of this assessment will provide valuable information about the appropriateness of using viewing time and choice reaction time as indicators of sexual interest. The future of sexual arousal assessment lies in the use of virtual reality and virtual environments that enable subjects to interact with the environment rather than passively viewing a stimulus. Figures, references