Little is known about men who have not yet committed child sexual abuse but may be at risk of doing so (potential offenders) and the factors that distinguish these men from undetected child sexual abuse offenders with a sexual interest in children (Dunkelfeld offenders). The present study describes and compares potential and Dunkelfeld offenders, which can be viewed as ideal target groups for (primary) prevention efforts with respect to child sexual abuse. Also, this study seeks to demonstrate the feasibility of using a telephone screening procedure to conduct research with these groups. Using a computer assisted telephone interview (CATI), data on demographics, mental health, sexuality, criminal history, and victim characteristics were collected from respondents in a nation-wide media campaign, which informed potential (re-)offenders of child sexual abuse of a research and treatment project. Many participants reported recurrent sexual fantasies involving minors, as well as related distress, suggesting a high prevalence of pedophilia and hebephilia. More than half feared they would sexually abuse a minor, and Dunkelfeld offenders reported 3.2 victims on average. Group comparisons revealed that Dunkelfeld offenders were, for example, more likely to perceive themselves being at risk of offending, compared to potential offenders. The results suggest that targeting potential and Dunkelfeld offenders could prove a worthwhile approach in the prevention of child sexual abuse.