Chile, New Zealand and Singapore announced their intention to initiate negotiations towards a trilateral closer economic partnership agreement, the Pacific Three (P3) at the APEC meeting in Los Cabos, Mexico in October 2002. On 3 June 2004, the P-3 accepted Brunei Darussalam as a founding member of the Agreement, thus becoming the P4.
Negotiations began in March 2003 and concluded with an agreement on 3 June 2005. At the same time, the Ministers announced the conclusion of parallel negotiations on an Environment Cooperation Agreement and a Labour Cooperation Memorandum of Understanding.
On 18 July 2005, the Agreement was signed by Chile, New Zealand and Singapore. A few weeks later, on 2 August 2005, Brunei signed the Agreement at the New Zealand Parliament, in Wellington.