PRojects IN Controlled Environments 2 (PRINCE2) is a structured project management method endorsed by the UK government as the project management standard for public projects. The methodology encompasses the management, control and organisation of a project. PRINCE2 is also used to refer to the training and accreditation of authorised practitioners of the methodology who must undertake accredited qualifications to obtain certification.

PRINCE2 is derived from an earlier method called PROMPTII and from PRINCE project management method, which was initially developed in 1989 by the Central Computer and Telecommunications Agency (CCTA) as a UK Government standard for information systems (IT) project management; however, it soon became regularly applied outside the purely IT environment. PRINCE2 was released in 1996 as a generic project management method. PRINCE2 has become increasingly popular and is now a de facto standard for project management in the UK.

Since 2006, the method has been revised and launched as "PRINCE2:2009 Refresh" in 2009. The name "PRINCE2" (instead of "PRINCE3" or similar) is kept to indicate that the method remains faithful to its principles. Nevertheless, it is a fundamental revision of the method from 1996 to adapt it to the changed business environment, to make the method simpler and "lighter", to address current weaknesses or misunderstandings, and to better integrate it with other OGC methods (ITIL, P3O, P3M3, MSP, M_o_R etc.).