Professionals who are likely to come into contact with children play an essential role in the protection of children, thus we aimed to study the criteria they use to identify and report child sexual abuse cases. Based on the Factorial Survey design, we presented 974 Spanish (90%) and Latin American professionals from six fields (Psychology, Social Services, Education, Health, Law and Security) with hypothetical situations of sexual interaction with minors (systematically varying the type of sexual act, the child's and the other person's sex and age, the use of coercion and the type of strategy employed to involve the child), in order to examine their perception of abuse and willingness to report. According to results, the factors or criteria that most impact assessments are age asymmetry and use of coercion. Specifically, professionals are significantly more likely to perceive abuse and intend to report it if the other person involved in the interaction is much older than the minor and/or uses a coercive strategy, especially force, drugs or blackmail. Another relevant criterion is the type of sexual act, since acts involving intercourse, digital penetration or oral sex are significantly more likely to be deemed as abuse and reported.