Western Climate Initiative, Inc. (WCI) is a 501(c)(3) non-profit corporation which administers the shared emissions trading market between the American state of California and the Canadian province of Quebec as well as separately administering the individual emissions trading systems in the Canadian province of Nova Scotia and American state of Washington.

The organization was originally founded in February 2007 by the governors of five western states with the goal of developing a multi-sector, market-based program to reduce greenhouse gas emissions; it was incorporated in its current form in 2011.

By July 2008, the initiative had expanded to include two more U.S. states (Montana and Utah) and four Canadian provinces (British Columbia, Manitoba, Ontario and Quebec).

Detailed design recommendations for a regional cap-and-trade program to reduce greenhouse gas emissions were released by the WCI in September 2008 and July 2010.

Some of the states that withdrew by late 2011 also intended to develop oil shale, hydraulic fracturing of natural gas and coal resources that would have broad impacts beyond climate on water, including more ocean acidification.

[10] For several years, the partners were the U.S. states of California, Montana, New Mexico, Oregon, Utah, and Washington, and the Canadian provinces of British Columbia, Manitoba, Ontario, and Quebec.

The observers included at various times Alaska, Colorado, Idaho, Kansas, Nevada, Wyoming, the province of Saskatchewan (which objects to WCI plans for a cap and trade system[9]), and the Mexican states of Baja California, Chihuahua, Coahuila, Nuevo Leon, Sonora and Tamaulipas.