Who sexually abuses children? We do not know how many adults sexually abuse children, but it is clear that there are more than official figures show, and that large numbers of individuals are engaging with CSA images. Most contact CSA is perpetrated by a person whom the child knows and trusts. Almost all individuals convicted of CSA are men, but perpetration by women may be more common than official data suggests. Perpetrators come from all walks of life, and ethnicity is not a predictor of CSA perpetration. What are the pathways to CSA offending? There are likely to be a number of different and complex pathways into CSA offending. Most adult perpetrators of CSA do not have extensive criminal histories or criminal lifestyles. The great majority of victims of CSA do not go on to commit CSA themselves; however, those who commit CSA are more likely than other adults to have experienced multiple forms of abuse as children, including physical, domestic or sexual abuse, and neglect. Social and cultural practices, as well as institutional and environmental settings, can provide a context for CSA to take place. Offences occur mostly in contexts of ordinary social interactions. Situations and locations can present individuals with opportunities to offend, and/or exert social pressure or weaken their moral restraints, leading to CSA. First offences often take place at times of depression, anxiety and stress for the perpetrator. What interventions are effective? Most individuals convicted of sexual offences, including CSA, are not reconvicted of further sexual offences. Few women and men convicted of online offences are reconvicted for sexual reoffences. It should be noted, however, that most CSA does not come to the attention of the authorities. Evidence is lacking regarding the effectiveness of programmes used in the UK to address sexual offending, particularly those specific to CSA; for example, current trauma-informed programmes used in the UK and based on the Good Lives Model have not yet been evaluated. The Core sex offender treatment programme in the UK was replaced after it was shown not to reduce sexual reoffending; however, individuals who completed similar programmes in other countries had lower rates of sexual reoffending than comparable individuals who did not. In the USA, Circles of Support and Accountability (CoSA) have been found to lead to fewer sexual reconvictions. Studies in other countries have shown that CoSA can help individuals released from prison to integrate into communities, which is associated with reducing reoffending. Providing interventions for individuals at risk of committing CSA is also important, as they may struggle with their sexual thoughts for some years before committing an offence, and many seek help prior to offending. Our 'Key messages from research' papers aim to provide succinct, relevant information for frontline practitioners and commissioners. They bring together the most up-to-date research into an accessible overview, supporting confident provision of the best possible resp...