The Independent Inquiry into Child Sexual Abuse (IICSA) in England and Wales was announced by the British Home Secretary, Theresa May, on 7 July 2014. The inquiry was established to examine how the country's institutions handled their duty of care to protect children from sexual abuse.

It was set up after investigations in 2012 and 2013 into the Jimmy Savile sexual abuse scandal revealed widespread abuse, including claims of abuse stretching back over decades by prominent media and political figures, and inadequate safeguarding by institutions and organisations responsible for child welfare. Originally the inquiry was intended to be a Panel Inquiry supported by experts, similar to the Hillsborough Independent Panel. However, after strenuous objections related to the panel's scope and its independence from those being investigated, and the resignation of its first two intended chairs, the inquiry was reconstituted in February 2015 as a statutory inquiry under the Inquiries Act 2005, giving it greatly increased powers to compel sworn testimony and to examine classified information.

The first two chairs appointed to the original panel inquiry were Baroness Butler-Sloss (appointed 8 July 2014, stepped down 14 July 2014) and Fiona Woolf (appointed 5 September 2014, stepped down 31 October 2014). The reasons for their withdrawal in each case were objections related to their perceived closeness to individuals and establishments which would be investigated. There were also objections to the shape of the inquiry itself, concerning testimony, the scope of inquiry, and lack of ability to compel witnesses to testify. In December 2014 it was reported that Theresa May was reconsidering arrangements for the inquiry. On 4 February 2015 May announced that the inquiry would be chaired by Dame Lowell Goddard, a New Zealand High Court judge who had no ties to the UK bodies and persons likely to be investigated. The existing panel was disbanded, and the inquiry was given new powers as a statutory inquiry.

The statutory inquiry opened on 9 July 2015, with an introductory statement by Dame Lowell Goddard. In November 2015, she announced that 12 separate investigations would be undertaken as part of the inquiry, including investigations into MPs, local councils, and church organisations. On 4 August 2016 May's successor as Home Secretary, Amber Rudd, announced that Goddard had resigned. In a statement, Goddard said that she had taken the decision "with regret", citing, among other reasons, the inquiry's "legacy of failure". Rudd announced on 11 August that Professor Alexis Jay would become the fourth chairman for the Inquiry.

In June 2017 the group Survivors of Organised and Institutional Abuse (Soia) withdrew "with deep regret" from the inquiry, as it was "not fit for purpose". They said that survivors had been "totally marginalised" and that the inquiry had descended into a "very costly academic report writing and literature review exercise". An IICSA spokesperson said that they regretted the withdrawal, but the inquiry would continue.

As of September 2021 IICSA had published sixteen reports, with three more to come, followed by a final report in 2022. In November 2020 IICSA published a 144-page report, Safeguarding in the Roman Catholic Church in England and Wales, which said that the Catholic Church of England and Wales "swept under the carpet" allegations of sex abuse by many individuals, including priests, monks and volunteers, in England and Wales. The report said about Vincent Nichols, a cardinal since 2014 and the leader of the Catholic church in England and Wales, "There was no acknowledgement of any personal responsibility", and that Nichols protected the reputation of the Church rather than protecting victims, and lacked compassion towards victims. On 2 September 2021 the inquiry published Child protection in religious organisations and settings - Investigation Report, after examining evidence from 38 groups, including sects from Christianity, Orthodox Judaism and Islam. "Shocking failings" and "blatant hypocrisy" in the way major UK religious groups handle child sex abuse allegations were found. The report said that some religious organisations were "morally failing" children, discouraging the reporting of abuse to protect reputations, blaming victims for their abuse, and responding to allegations using religious dogma.