The non-consensual sharing of private sexual images (so-called ‘revenge pornography’) has become an increasingly prominent topic in social and legislative discussions about sexual crime but has received relatively little attention within psychological research. Here, we leveraged existing theorizing in the area of sexual offending proclivity to systematically develop and validate a measure of beliefs about this type of offending. There is currently a lack of validated assessment tools in this area, and these are important to better understand the role of offense-supportive cognition in predicting both proclivity of these offenses and judgements of both victims and perpetrators. Using an international community sample ( N = 511) we found our ‘Beliefs about Revenge Pornography Questionnaire (BRPQ)’ to be comprised of four underpinning domains: ‘Victims as Promiscuous’, ‘Victim Harm’, ‘Avoiding Vulnerable Behaviors’ and ‘Offense Minimization’. Concurrent validity is demonstrated through relationships with trait empathy, belief in a just world, dark personality traits and rape myth acceptance. Randomly dividing the sample, we also show that the BRPQ was associated with both proclivity ( n = 227) and social judgements of this type of offending ( n = 232). Implications and future directions are discussed. An open-access preprint is available at https://psyarxiv.com/6qr7t/ .