The Security Industry Authority (SIA) is the organisation responsible for regulating the private security industry. They are an independent body reporting to the Home Secretary, under the terms of the Private Security Industry Act 2001. Their mission is to regulate the private security industry effectively; to reduce criminality, raise standards and recognise quality service. The SIA remit covers the United Kingdom.

The SIA have two main duties. One is the compulsory licensing of individuals undertaking designated activities within the private security industry; the other is to manage the voluntary Approved Contractor Scheme, which measures private security suppliers against independently assessed criteria.

SIA licensing covers manned guarding (including security guarding, door supervision, close protection, cash and valuables in transit, and public space surveillance using CCTV), key holding and vehicle immobilising. Licensing ensures that private security operatives are ‘fit and proper’ persons who are properly trained and qualified to do their job.