Also see our entry in the Boston Open Guide, with a list of locations featured on the map.
Feel free to add entries for anything missing from the guide that is included on the map.

Business, Employment, & Development

Bost A Better City: Formerly the Artery Business Committee.
Intl The Boston Fair Trade Coalition
GBos Business Summit for a Sustainable Boston: Not to be confused with Sustainable Business Network below.
Camb Cambridge Local First: Promotes locally owned businesses.
Intl Ceres: Promotes socially respsonible business practices.
GBos City Squares: Promotes neighborhood businesses.
Intl Corporate Accountability International
Intl Design that Matters
Intl Ecologic Development Fund
Intl Boston Chapter of Engineers without Borders
Natl Environmental Careers Organization: Environmental internships for students
Natl Somerville Chapter of Groundwork USA: Works to develop brownfields.
GBos Healthy Homes Cleaning
Intl idealist: Internships and employment opportunities in the non-profit sector.
GBos Metropolitan Area Planning Council
Intl Small-scale Sustainable Infrastructure Development Fund
Intl Stockholm Environment Institute: Sustainable development research.
GBos Sustainable Business Network of Greater Boston: Not to be confused with Business Summit for a Sustainable Boston above.
Natl Sustainable Endowments Institute: Promotes socially responsible investment of university endowments.
Intl Tellus Institute: Advancing the transition to a sustainable, equitable, and humane global civilization.

Civics, Politics & Social Involvement

Camb Area 4 Neighborhood Colationa
Camb Association of Cambridge Neighborhoods
Camb Agassiz Neighborhood Council
Bost Boston Coop Network
Intl Boston IndyMedia
Camb Cambridge Civic Journal
Camb Cambridge Cohousing
Camb Cambridge Community Television
GBos Democracy Center: A venue which hosts a variety of civic events.
Natl Drinking Liberally Cambridge: A national network of Democratic drinking clubs.
Intl Greendrinks: A monthly meeting of environmental professionals and other interested parties.
Mass Cambridge-Somerville Chapter of the Green-Rainbow Party
Intl idealist
Mass Massachusetts League of Environmental Voters: Search for volunteer opportunities.
GBos Single Volunteers Boston
GBos Socializing for Justice
Somr Somerville Community Access Television
Natl Volunteer Match: Search for volunteer opportunities.
Natl Volunteer Solutions: Search for volunteer opportunities in this United Way maintained database.

Energy & Climate

GBos Boston Area Solar Energy Association
Camb Cambridge Energy Alliance
Mass Cape Wind
Mass Clean Power Now
Intl MA Chapter of Climate Action Network
Natl Consortium for Energy Efficiency
Camb Green Decade Cambridge: Formerly Cambridge Climate Action
Mass greenGoat: Promotes green building and demolotion.
Natl The Green Roundtable: Promotes green building.
GBos Hull Wind
Mass Massachusetts Consumers Energy Alliance: A supporter of the now defunct Solar Boston.
Mass MassSAVE: Residential energy conservation services.
NewE New England GreenStart: Select alternative energy sources as your electricity provider.
NewE Northeast Sustainable Energy Association
Natl Prometheus Institute: Conducts solar energy industry research.

(Environmental) Justice & Equity

NewE ACE: alternatives for community and environment
Intl Dollars & Sense: The Magazine of Economic Justice
GBos Eagle Eye Institute: Hands-on environmental learning for underserved urban youth of color.
Intl Grassroots International
United for Justice with Peace: A coalition of peace and justice organizations in Greater Boston.

Flora & Fauna

Mass Massachusetts Horticultural Society
NewE New England Wild Flower Society

Food & Gardens

GBos Boston Organics: Home delivery of organic produce.
Bost Boston Public Market
Bost Boston Vegetarian Society
Camb CitySprouts: Schoolyard gardens
Mass Department of Agriculture: Maintains several resources including the Massgrown map.
GBos EarthWorks Projects: Promotes and maintains urban orchards.
GBos Edible Boston: A quarterly magazine, "Celebrating the Abundance of Local Foods, Season by Season."
GBos Equal Exchange: A fair trade importer of organic coffee, tea, sugar, and chocolate.
GBos The Food Project: Organic produce grown by local youth
Mass Garden Club Federation of Massachusetts
GBos Harvest Co-op: A cooperatively owned supermarket.
GBos In Season
Camb Henrietta's Table: Local, organic food restaurant; Local agricultural product aggregator resells with street stalls and CSA-style delivery.
Camb Kendall Square Farmers' Market: Thursdays, 11:00-2:30
GBos Massachusetts Farmers' Markets
NewE Northeast Organic Farming Association: MA NOFA maintains a list of CSAs (local farms that offer product subscriptions).
NewE red tomato: Promotes and sells locally grown and fair-traded produce.
Camb Veggie Planet Restaurant

Other & General

Camb Cambridge Camping: Runs a variety of daycamps for local youth.
NewE Conservation Law Foundation
Natl Environmental Action
GBos "e" - The Environmental Learning & Action Center
Natl Environmental League of Massachusetts is the MA Chapter of the National Wildlife Federation
NewE Environment Northeast
Natl Green Corps: Not affiliated with, but similar to, AmeriCorps /City Year: trains environmental organizers.
Natl National Environmental Law Center: "Dedicated to enforcing anti-pollution laws."
Natl MA Chapter of the State PIRGs has spun off their environmental efforts: A federation of independent and locally based Public Interest Research Groups.
Natl Second Nature: Advocates for more environmentally responsible higher education.
Natl MA Chapter of the Sierra Club
Mass Silent Spring Institute: Researches pollution and women's health.
GBos Urban Ecology Institute: Education as well as urban ecosytem research and advocacy.
GBos Youth Enrichment Services: Outdoor sports to foster life-long respect for self, others, and the environment.

Open Space & Parks

GBos Alewife Neighbors
GBos Alewife Study Group
Natl Massachusetts Chapter of the Audubon Society: Works to protect habitat, especially that of birds, and has a sanctuary in Boston.
NewE Boston Chapter of the Appalachian Mountain Club: The AMC promotes the protection and enjoyment of the Northeast outdoors.
Bost Boston HarborWalk: The Harbor Walk is a path connecting numerous parks and other features on the waterfront.
Bost Boston Natural Areas Network: "works to preserve, expand and improve urban open space through community organizing"
Mass Conservation and Recreation Campaign: Campaigns for the adequate funding and maintenance of public lands.
Bost The Emerald Necklace Conservancy: Works to preserve Frederick Law Olmsted's Legacy
Bost The Esplanade Association: Advocates for the maintenance and enhancement of Boston's riverfront park.
Bost The Forest Hills Educational Trust
Camb Friends of Alewife
GBos Friends of the Blue Hills
GBos Friends of the Middlesex Fells Reservation
Bost Mount Auburn Cemtery
NewE Northeast Wilderness Trust
NewE New England Forestry Foundation
Natl The Trust for Public Land
Mass The Trustees of Reservations: Preserves open space through acquisition and conservation restrictions.

Reduce, Reuse, Recycle

MIT Reuse

The original electronic forum to exchange/discard free goods, and its clones:

Intl Freecycle
GBos Greater Boston Reuse

GBos Building Materials Resource Center

Accepts donated new and used building materials and sells them at a deep discount.

Camb The Garment District

Natl Inktec Zone

Printer ink and toner refill/refurbishing.

Mass MassRecycle

NewE Northeast Waste Management Officials' Association

Natl Product Stewardhsip Institute

GBos The Recycle Shop

The Children's Museum accepts and sells a variety of materials for use in craft projects.

NewE Toxics Action Center

Provides support for neighborhood groups fighting pollution.

Mass Toxics Use Reduction Initiative

Mass WasteCap

Directory of recyclers, primarily oriented towards businesses.

Transit

NewE AltWheels: Sustainable transportation advocacy.
GBos Bay Circuit Alliance: Works towards the completion of a circum-Boston path and greenway.
Intl Bikes not Bombs: A Roxbury based bicycle advocacy group that also refurbishes and donates bicycles.
Camb Cambridge Green Streets Initiative: Promotes monthly auto-free days, particularly for school children.
Camb Cambridge Walks
GBos Charles River Wheelmen: A social bicycling club.
GBos CITY minus TRAFFIC: An interesting proposal for the Allston/Brighton/Cambridge area.
Intl Boston Chapter of Critical Mass (alternate): Promotes bicyling and other human powered transportation.
Camb EZRide shuttle: North Station - East Cambridge - Cambridgeport
GBos Friends of the Community Paths
Intl Health Effects Institute: Conducts research on transit and non-transit related air pollution.
GBOS LivableStreets Alliance: Promotes a hollistic approach to urban transit and street-scape/-life.
GBos LMA Shuttle: Harvard - MIT - Longwood Medical Area
GBos Massachusetts Bay Transit Authority
Mass Massachusetts Bicycle Coalition
GBos Minuteman Bikeway
NewE New England Mountain Bike Association
GBos PlanetTran: A taxi company with an all-hybrid fleet offering service to/from Logan airport.
Somr Somerville Transportation Equity Partnership
GBos Walk Boston: Promotes walking for transportation and recreation.
GBos Zipcar: A subscription car sharing service.

Water

GBos The Boston Harbor Association
GBos The Charles River Conservancy
GBos Charles River Watershed Association
Mass commonwaters: Massachusetts Watershed Coalition
Camb Friends of Fresh Pond
GBos Massachusetts Bays Estuary Association: Runs the Think Again. Think Blue. campaign.
GBos Massachusetts Water Resources Authority: Manages the sewer and drinking water supply for much of Eastern Massachusetts.
GBos Mystic River Watershed Association
NewE New England Aquarium
GBos Save the Harbor / Save the Bay
NewE Southern New England Chapter of the Soil & Water Conservation Society