The 1999 Seattle WTO protests, sometimes referred to as the Battle of Seattle, were a series of anti-globalization protests surrounding the WTO Ministerial Conference of 1999, where members of the World Trade Organization (WTO) convened at the Washington State Convention and Trade Center in Seattle, Washington on November 30, 1999. The Conference was to be the launch of a new millennial round of trade negotiations.

The negotiations were quickly overshadowed by massive street protests outside the hotels and the Washington State Convention and Trade Center. The protests were nicknamed "N30", akin to J18 and similar mobilizations. The large scale of the demonstrations, estimated at no fewer than 40,000 protesters, dwarfed any previous demonstration in the United States against a world meeting of any of the organizations generally associated with economic globalization, such as the WTO, the International Monetary Fund, and the World Bank.

Planning for the actions began months in advance and included local, national, and international organizations. Among the most notable participants were national and international nongovernmental organizations (NGOs) such as Global Exchange (especially those concerned with labor issues, the environment, and consumer protection), labor unions (including the AFL–CIO), student groups, religion-based groups (Jubilee 2000), and anarchists (some of whom formed a black bloc). The protests also drew support from some political conservatives, such as American presidential candidate and commentator Pat Buchanan.

The coalition was loose, with some opponent groups focused on opposition to WTO policies (especially those related to free trade), with others motivated by prolabor, anticapitalist, or environmental agendas. Many of the NGOs represented at the protests came with credentials to participate in the official meetings, while also planning various educational and press events. The AFL–CIO, with cooperation from its member unions, organized a large permitted rally and march from Seattle Center to downtown.

However, others were more interested in taking direct action, including both civil disobedience and acts of vandalism and property destruction to disrupt the meeting. Several groups were loosely organized together under the Direct Action Network (DAN), with a plan to disrupt the meetings by blocking streets and intersections downtown to prevent delegates from reaching the convention center, where the meeting was to be held. The black bloc was not affiliated with DAN, but was responding to the original call for autonomous resistance actions on November 30 issued by People's Global Action.

Of the different coalitions that aligned in protest were the "teamsters and turtles" – a blue–green alliance consisting of the teamsters (trade unions) and environmentalists.

Certain activists, including locals and an additional group of anarchists from Eugene, Oregon (where they had gathered that summer for a music festival), advocated more confrontational tactics, and conducted vandalism of corporate properties in downtown Seattle. In a subsequent communique, they listed the particular corporations targeted, which they considered to have committed corporate crime.

On July 12, the Financial Times reported that the latest United Nations Human Development report advocated "principles of performance for multinationals on labour standards, fair trade and environmental protection ... needed to counter the negative effects of globalisation on the poorest nations". The report itself argued, "An essential aspect of global governance is responsibility to people—to equity, to justice, to enlarging the choices of all".