In 1994, the City of Seattle and the Parks Department began to notice something wrong with trees in city parks. Research found that Seattle’s 2,500 acres of forested city parks were at risk from invasive plants such as English Ivy, Himalayan blackberry, and bindweed. In 2004, experts projected that within 20 years about 70 percent of Seattle’s forested parkland trees would be dead. Previously, park-goers, non-profits, and government agencies worked to remove invasive species independently. Rather than helping the problem, however, these piecemeal efforts placed an undue strain on the city’s existing resources. Saving the parks required a shared effort involving community members, experts in forestry, and the departments that held park resources. This case study tells the story of Green Seattle Partnership, formed in 2004 with the aim of arming citizens to help the city’s trees in partnership with the Department of Parks, Public Utilities, and the Office of Sustainability and Environment.