Imagine a Tupperware party, but for the tree-hugging set. That’s the vision, sort of, of Global Action Plan, a nonprofit organization that is promoting the formation of EcoTeams, grassroots groups dedicated to helping neighbors create sustainable lifestyles and livable communities. The teams, which are currently in eight cities around the country, meet every other week for three or four months to discuss how to do their part for Mom Earth. The program is based on the theory of social diffusion, which holds that people need four months to change a habit and populations need 15 percent involvement to create a social movement. Last year, households participating in EcoTeams in Columbus, Ohio, cut their average garbage by 41 percent and saved $291 through waste reduction and energy conservation. One participant, Robin Wigney, said being part of a group made people feel more accountable for their actions, while the support system and shared information made it easier to make environmentally friendly choices: “The biggest hurdle in participating in this program is finding ways to make it convenient in your household — because the way our culture works, it’s got to be convenient.”