350 Chicago is a spinoff of 350.org, a left-of-center environmentalist organization that advocates for ending use of conventional fuels and eliminating all carbon emissions. 350 Chicago advocates for all government and private institutions to cease financial support of conventional energy companies and supports the Green New Deal. 
350 Chicago has been described by the city of Chicago pension boards as the leading organizer in protests for divestment from fossil fuel companies.  350 Chicago is also a sponsor of the Illinois Clean Energy Job Act (CEJA), an environmentalist proposal that proponents claim is even stricter than the Green New Deal.  CEJA contains plans to combat climate change by financing the transition to an infrastructure that relies on environmentalist energy, banning the use of fossil fuels, and prioritizing the government contracting of workers from ethnic minority populations. 
After the results of the 2020 general election, 350 Chicago joined 380 organizations in support of a proposed executive order written by the Center for Biological Diversity calling on President Joe Biden to enact environmental policy that resembles the Green New Deal. The draft of the executive order would end the development of new fossil fuel infrastructure, ban fracking on public land, and eliminate funding for fossil fuels. The order would also grant powers to the Department of Justice (DOJ) to protect left-of-center environmentalist protesters and “seek damages” for “environmental harms” done by the fossil fuel industry. 
Larry Coble and Melissa Brice founded 350 Chicago in May 2013. Coble has participated in environmentalist activism since the 1990s, and in the 1980s, he participated in campaigns advocating against American involvement in wars in Central America. Brice began as an environmental activist by joining a protest of the Keystone XL pipeline during the Obama administration and later attended Al Gore’s Climate Reality Project training in August of 2014. 
350 Chicago is registered as a 501(c)(3) nonprofit organization. Its financial data is not publicly available, as it reports less than $50,000 a year in revenue.