The negotiations for the Trans-Pacific Partnership Agreement were held between 12 countries between 2008 and 2015. The negotiations were aimed at obtaining an agreement between the Trans-Pacific Strategic Economic Partnership Agreement parties Brunei, Chile, Singapore and New Zealand, as well as the Australia and the United States.

Brunei—a member of the Asia Pacific Economic Cooperation (APEC) since 1989— has played an important role in the formation of the earlier trade agreements that led up to the creation of TPP in 2005. In 2000 Brunei hosted the pivotal meeting of APEC where discussion began and later the ASEAN Regional Forum (ARF) in July 2002.^[7]

By 2001 New Zealand and Singapore had already joined in the New Zealand/Singapore Closer Economic Partnership (NZSCEP). The Trans-Pacific Strategic Economic Partnership Agreement (Trans-Pacific SEP) built on the NZSCEP.^[8]: 5

During the 2002 Asia-Pacific Economic Cooperation (APEC) Leaders' Meeting in Los Cabos, Mexico, Prime Ministers Helen Clark of New Zealand, Goh Chok Tong of Singapore and Chilean President Ricardo Lagos began negotiations on the Pacific Three Closer Economic Partnership (P3-CEP).^[8]: 5 According to the New Zealand Department of Foreign Affairs and Trade,^[8]: 5

The shared desire was to create a comprehensive, forward-looking trade agreement that set high-quality benchmarks on trade rules, and would help to promote trade liberalisation and facilitate trade within the APEC region.

— Ministry of Foreign Affairs and Trade, New Zealand 2005

Brunei first took part as a full negotiating party in April 2005 before the fifth, and final round of talks.^[9] Subsequently, the agreement was renamed to TPSEP (Trans-Pacific Strategic Economic Partnership agreement or Pacific-4). Negotiations on the Trans-Pacific Strategic Economic Partnership Agreement (TPSEP or P4) were concluded by Brunei, Chile, New Zealand and Singapore on 3 June 2005,^[2] and entered into force on 28 May 2006 for New Zealand and Singapore, 12 July 2006 for Brunei, and 8 November 2006 for Chile.^[10]

The original TPSEP agreement contains an accession clause and affirms the members' "commitment to encourage the accession to this Agreement by other economies".^[9][11] It is a comprehensive agreement, affecting trade in goods, rules of origin, trade remedies, sanitary and phytosanitary measures, technical barriers to trade, trade in services, intellectual property, government procurement and competition policy. Among other things, it called for reduction by 90 percent of all tariffs between member countries by 1 January 2006, and reduction of all trade tariffs to zero by the year 2015.^[12]

Although original and negotiating parties are members of the Asia-Pacific Economic Cooperation (APEC), the TPSEP (and the TPP it grew into) are not APEC initiatives. However, the TPP is considered to be a pathfinder for the proposed Free Trade Area of the Asia Pacific (FTAAP), an APEC initiative.

In January 2008, the US agreed to enter into talks with the Pacific 4 (P4) members regarding trade liberalisation in financial services.^[13] On 22 September 2008, US Trade Representative Susan C. Schwab announced that the US would be the first country to begin negotiations with the P4 countries to join the TPP, planning to start the first round of talks in early 2009.^[14][15] In November 2008, Australia, Vietnam, and Peru announced that they would also join the P4 trade bloc.^[16][17] In October 2010, Malaysia announced that it had also joined the TPP negotiations.^[18][19][20]

After the inauguration of President Barack Obama in January 2009, the anticipated March 2009 negotiations were postponed. However, in his first trip to Asia in November 2009, President Obama reaffirmed the United States' commitment to the TPP, and on 14 December 2009, new US Trade Representative Ron Kirk notified Congress that President Obama planned to enter TPP negotiations "with the objective of shaping a high-standard, broad-based regional pact".^[21] On the last day of the 2010 APEC summit, leaders of the nine negotiating countries endorsed the proposal advanced by US President Barack Obama that set a target for settlement of negotiations by the next APEC summit in November 2011.^[22]

In 2010, Canada had become an observer in the TPP talks, and expressed interest in officially joining,^[23] but was not committed to join, purportedly because the US and New Zealand blocked it because of concerns over Canadian agricultural policy (i.e. supply management)—specifically dairy—and intellectual property-rights protection.^[24] Several pro-business and internationalist Canadian media outlets raised concerns about this as a missed opportunity. In a feature in the Financial Post, former Canadian trade-negotiator Peter Clark claimed that the US Obama Administration had strategically outmaneuvered the Canadian Harper Government. Wendy Dobson and Diana Kuzmanovic for The School of Public Policy, University of Calgary, argued for the economic necessity of the TPP to Canada.^[25] Embassy warned that Canada's position in APEC could be compromised by being excluded from both the US-oriented TPP and the proposed China-oriented ASEAN +3 trade agreement (or the broader Comprehensive Economic Partnership for East Asia).^[19][20][26]

In February 2012 a call for co-operation between the WTO and Economic Partnership Agreements (also termed regional trade agreements) like the TPP came after Pierre Lellouche described the sentiment of the Doha round negotiations; "Although no one wants to say it, we must call a cat a cat (failure is failure)...".^[27]

In June 2012, Canada and Mexico announced that they were joining the TPP negotiations.^{[28][29][30][31]} Mexico's interest in joining was initially met with concern among TPP negotiators about its customs policies.^[24] Canada and Mexico formally became TPP negotiating participants in October 2012, following completion of the domestic consultation periods of the other nine members.^[32][33][34]

On 23 July 2013, Japan officially joined the TPP negotiations . According to the Brookings Institution, Prime Minister Abe's decision to commit Japan to joining the TPP should be understood as a necessary complement to his efforts to stimulate the Japanese economy with monetary easing and the related depreciation of the Yen. These efforts alone, without the type of economic reform the TPP will lead to, are unlikely to produce long-term improvements in Japan's growth prospects.^[35]

In April 2013 APEC members proposed, along with setting a possible target for settlement of the TPP by the 2013 APEC summit, that World Trade Organization (WTO) members set a target for settlement of the Doha Round mini-package by the ninth WTO ministerial conference (MC9), also to be held around the same time in Bali.^[36]

A set of draft documents leaked in late-2013 indicated, that public concern had little impact on the negotiations.^[37] They also indicated there are strong disagreements between the US and negotiating parties regarding intellectual property, agricultural subsidies, and financial services.^[38]

On 1 August 2015 a spokesman for Australia's Trade Minister Andrew Robb confirmed, that no conclusion had been reached during the Ministerial Meeting in Hawaii, U.S., in late July 2015. Robb told the media that Australia had made progress on sugar and dairy matters, but the balance that the Australian government was seeking had not yet been finalized.^[39]

Nineteen formal rounds of TPP negotiations were held from 2010–2013:^[40][41]

After the 19th round of formal meetings, negotiations stopped taking the form of official rounds, but other meetings, such as Chief Negotiators Meetings and Ministers Meetings, continue.