Company lists · Data refreshed September 2026

Top 25 Environmental advocacy organizations based in Washington, United States

Name: Environmental advocacy organizations based in Washington, United States
Creator: RevenueBase
License: https://creativecommons.org/licenses/by/4.0/

Compiled by the RevenueBase Data Team Data refreshed Sep 19, 2026 76 companies tracked

RevenueBase identified 76 environmental advocacy organizations headquartered in Washington, United States as of September 2026 and tracks 3,048 professional contacts across them, including 1,309 with verified work emails. Washington is the largest hub.

This list covers environmental advocacy organizations headquartered in Washington, United States, matched on what each company actually does as described in its own words. Ranked by team size, largest first. Every row shows the company's own description, its RevenueBase Smart Search rating, and when it was last checked. Data refreshed September 19, 2026.

Published by RevenueBase, a B2B data infrastructure company. This list was built with RevenueBase Smart Search, the natural-language company search RevenueBase customers use to build their own targeted lists and unlock verified emails and direct dials at the companies on them. How these lists are built and judged.

How to read this list HQ checked on every row RevenueBase Smart Search rating on every row Refreshed Sep 19, 2026 86% judged on-target in blind review

76Companies

3,048Contacts tracked

1,309Verified emails

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The 25 largest environmental advocacy organizations based in Washington, United States

Ranked by team size

Top 25 of 76 environmental advocacy organizations based in Washington, United States, ranked by team size, largest first. Data refreshed Sep 19, 2026. RevenueBase Smart Search rates how each company's information relates to environmental advocacy organizations: strong evidence (its own description names it), partial (names part of it), indirect (matched on the rest of its profile rather than the description shown). Click a contact count to view that company's people.
#	Company	RevenueBase Smart Search	Headquarters	Employees	Contacts
1	Clean Water Action	Partial evidence	Washington, DC, United StatesHQ checked Sep 19, 2026	51-200	366 contacts →
	Partial evidence “Since our founding during the campaign to pass the landmark Clean Water Act in 1972, Clean Water Action has worked to win strong health and environmental protections by bringing…” Source: RevenueBase Database · checked Sep 19, 2026
2	National Parks Conservation Association	Indirect evidence	Washington, DC, United StatesHQ checked Sep 19, 2026	51-200	303 contacts →
	Indirect evidence “Named a USA Top Workplace in 2023** For a century, National Parks Conservation Association has been a powerful independent voice working to strengthen and protect America's…” Source: RevenueBase Database · checked Sep 19, 2026
3	League Of Conservation Voters	Indirect evidence	Washington, DC, United StatesHQ checked Sep 19, 2026	51-200	218 contacts →
	Indirect evidence “LCV believes our earth is worth fighting for because everyone has a right to clean air, water, and a safe, healthy community.” Source: RevenueBase Database · checked Sep 19, 2026
4	The Wilderness Society	Indirect evidence	Washington, DC, United StatesHQ checked Sep 19, 2026	51-200	199 contacts →
	Indirect evidence “The Wilderness Society (TWS) is the leading conservation organization working to protect America’s wild places and public lands for the health of local communities, wildlife, and…” Source: RevenueBase Database · checked Sep 19, 2026
5	American Rivers	Indirect evidence	Washington, DC, United StatesHQ checked Sep 19, 2026	51-200	147 contacts →
	Indirect evidence “American Rivers protects wild rivers, restores damaged rivers, and conserves clean water for people and nature.” Source: RevenueBase Database · checked Sep 19, 2026
6	earthday.org	Partial evidence	Washington, DC, United StatesHQ checked Sep 19, 2026	11-50	144 contacts →
	Partial evidence “EARTHDAY.ORG’s mission is to diversify, educate and activate the environmental movement worldwide.” Source: RevenueBase Database · checked Sep 19, 2026
7	Earthworks	Partial evidence	Washington, DC, United StatesHQ checked Sep 19, 2026	11-50	126 contacts →
	Partial evidence “EARTHWORKS is a nonprofit organization dedicated to protecting communities and the environment from the impacts of irresponsible mineral and energy development while seeking…” Source: RevenueBase Database · checked Sep 19, 2026
8	Environmental Working Group	Partial evidence	Washington, DC, United StatesHQ checked Sep 19, 2026	51-200	120 contacts →
	Partial evidence “The Environmental Working Group is a non-profit, non-partisan organization dedicated to protecting human health and the environment.” Source: RevenueBase Database · checked Sep 19, 2026
9	Environmental LAW Institute	Partial evidence	Washington, DC, United StatesHQ checked Sep 19, 2026	11-50	102 contacts →
	Partial evidence “The Environmental Law Institute (ELI) makes law work for people, places, and the planet.” Source: RevenueBase Database · checked Sep 19, 2026
10	Greenpeace USA	Indirect evidence	Washington, DC, United StatesHQ checked Sep 19, 2026	51-200	97 contacts →
	Indirect evidence “Founded in 1971, Greenpeace began when a small group of activists sailed from Vancouver to protest nuclear testing at Amchitka, Alaska.” Source: RevenueBase Database · checked Sep 19, 2026
11	Earthrights International	Indirect evidence	Washington, DC, United StatesHQ checked Sep 19, 2026	11-50	82 contacts →
	Indirect evidence “EarthRights International is a nongovernmental, nonprofit organization that combines the power of law and the power of people in defense of earth rights.” Source: RevenueBase Database · checked Sep 19, 2026
12	Center For International Environmental LAW Ciel	Partial evidence	Washington, DC, United StatesHQ checked Sep 19, 2026	51-200	74 contacts →
	Partial evidence “The Center for International Environmental Law (CIEL) uses the power of the law to protect the environment, promote human health, and ensure a just and sustainable society.” Source: RevenueBase Database · checked Sep 19, 2026
13	Ecoamerica	Indirect evidence	Washington, DC, United StatesHQ checked Sep 19, 2026	11-50	53 contacts →
	Indirect evidence “ecoAmerica grows the base of popular support for climate solutions in America with research-driven marketing, partnerships, and national programs that connect with Americans' core…” Source: RevenueBase Database · checked Sep 19, 2026
14	Friends Of The Earth U.S	Indirect evidence	Washington, DC, United StatesHQ checked Sep 19, 2026	51-200	51 contacts →
	Indirect evidence “Friends of the Earth is a bold and fearless voice for justice and the planet.” Source: RevenueBase Database · checked Sep 19, 2026
15	OIL Change International	Partial evidence	Washington, DC, United StatesHQ checked Sep 19, 2026	11-50	47 contacts →
	Partial evidence “Oil Change International is a research, communication, and advocacy organization focused on exposing the true costs of fossil fuels and facilitating the coming transition towards…” Source: RevenueBase Database · checked Sep 19, 2026
16	Public Justice	Indirect evidence	Washington, DC, United StatesHQ checked Sep 19, 2026	11-50	45 contacts →
	Indirect evidence “Public Justice pursues high impact lawsuits to combat social and economic injustice, protect the Earth’s sustainability, and challenge predatory corporate conduct and government…” Source: RevenueBase Database · checked Sep 19, 2026
17	Mighty Earth	Partial evidence	Washington, DC, United StatesHQ checked Sep 19, 2026	11-50	44 contacts →
	Partial evidence “Mighty Earth is a global environmental organization that works to make a lasting difference for the planet and its people with a focus on forests, sustainable agriculture, and…” Source: RevenueBase Database · checked Sep 19, 2026
18	Environmental Integrity Project	Indirect evidence	Washington, DC, United StatesHQ checked Sep 19, 2026	11-50	40 contacts →
	Indirect evidence “EIP combines research, reporting, and media outreach to spotlight illegal pollution, expose political intimidation of enforcement staff, and encourage federal and state agencies…” Source: RevenueBase Database · checked Sep 19, 2026
19	Conservation Nation	Indirect evidence	Washington, DC, United StatesHQ checked Sep 19, 2026	n/a	39 contacts →
	Indirect evidence “In the fight to save endangered animals and the planet, we need every smart voice and solution at the table.” Source: RevenueBase Database · checked Sep 19, 2026
20	Alaska Wilderness League	Partial evidence	Washington, DC, United StatesHQ checked Sep 19, 2026	11-50	38 contacts →
	Partial evidence “As the only DC-based environmental group focused on protecting Alaska’s wild places, Alaska Wilderness League’s mission is to lead the effort to preserve Alaska’s wild lands and…” Source: RevenueBase Database · checked Sep 19, 2026
21	Environmental And Energy Study Institute Eesi	Partial evidence	Washington, DC, United StatesHQ checked Sep 19, 2026	11-50	36 contacts →
	Partial evidence “The Environmental and Energy Study Institute (EESI) is a nonprofit organization established in 1984 by a bipartisan Congressional caucus to provide timely, credible information…” Source: RevenueBase Database · checked Sep 19, 2026
22	The Partnership Project	Indirect evidence	Washington, DC, United StatesHQ checked Sep 19, 2026	51-200	35 contacts →
	Indirect evidence “THE PARTNERSHIP PROJECT,(PP) is a 501(c)(3) non-profit organization based in WASHINGTON, District of Columbia, United States.” Source: RevenueBase Database · checked Sep 19, 2026
23	Global Council For Science And The Environment Gcse	Partial evidence	Washington, DC, United StatesHQ checked Sep 19, 2026	n/a	34 contacts →
	Partial evidence “The Global Council for Science and the Environment (GCSE) is a nongovernmental organization established in 1990 that advances the use of science to inform environmental…” Source: RevenueBase Database · checked Sep 19, 2026
24	Earthshare	Indirect evidence	Washington, DC, United StatesHQ checked Sep 19, 2026	11-50	33 contacts →
	Indirect evidence “EarthShare recognizes the power and influence that committed individuals can have for our planet.” Source: RevenueBase Database · checked Sep 19, 2026
25	National Environmental Education Foundation Neef	Partial evidence	Washington, DC, United StatesHQ checked Sep 19, 2026	11-50	33 contacts →
	Partial evidence “Congressionally chartered in 1990, NEEF's mission is to make the environment more accessible, relatable, relevant, and connected to the daily lives of all Americans.” Source: RevenueBase Database · checked Sep 19, 2026

RevenueBase Smart Search

RevenueBase Smart Search assesses information from a company’s LinkedIn profile, information supplied directly by the company, its website, and other publicly available sources. It uses that information to rate how closely the company relates to this list’s category: environmental advocacy organizations. Every row carries its rating and the description the rating was read from, so each one can be checked rather than taken on trust.

Strong evidence: The company's own public description of its business names environmental advocacy organizations.
Partial evidence: Its own public description names part of environmental advocacy organizations, so it works in or next to the category without describing itself that way.
Indirect evidence: The description shown does not name environmental advocacy organizations. The match rests on the rest of the company's public profile rather than the one sentence quoted here, so this is the rating to check first.

RevenueBase Smart Search is how these lists are built: RevenueBase's data engine and AI assemble the companies that match a category defined in a user's own words, so a list can be about what companies actually do rather than about whichever industry code they were filed under.

Showing 25 of 76 environmental advocacy organizations based in Washington, United States

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Environmental advocacy organizations based in Washington, United States at a glance

As of Sep 19, 2026

42.9%Verified-email coverage

40.1Average contacts per company

11-50Median size (employees)

100.0%Largest-city concentration · Washington

Sep 19, 2026Page data refreshed

Companies by employee count

1-10

11-50

51-200

201-500

501-1,000

Email recency for this list is measured across the whole United States list rather than for Washington, so it is reported there. Company counts and contact totals on this page are exact for Washington, over 76 companies.

How this list was built

Company categories are rarely black and white. RevenueBase reads each company's own description of its business to decide whether it belongs among environmental advocacy organizations, so some rows will be adjacent to the category rather than pure plays. The description and RevenueBase Smart Search rating on every row are there so you can check each match yourself.

Source: The RevenueBase company graph: 60 million companies and 398.9 million professional contacts resolved from primary sources, queried with RevenueBase Smart Search, the natural-language company search available to every RevenueBase user.
What qualifies: Companies headquartered in Washington, United States whose own description of what they do matches “environmental advocacy organizations”. Matching reads each company's description, not its industry code or its name.
RevenueBase Smart Search: RevenueBase Smart Search is how this list is assembled and how each row is rated. RevenueBase's data engine and AI assess a company's LinkedIn profile, information supplied directly by the company, its website and other publicly available information, then relate it to a category defined in a user's own words. Each row is rated strong evidence (its own description names environmental advocacy organizations), partial evidence (it names part of the category) or indirect evidence (the description shown names none of it and the match rests on the rest of the company's profile). The description supporting each rating is quoted on the row.
What we exclude: Companies whose own description does not clearly place them among environmental advocacy organizations, and records with no verified work email. Companies headquartered outside Washington are excluded even when they keep an office there.
Match quality: In blind human judging of this matching method, 86% of matched companies were on target. Expect roughly 1 in 7 rows to be adjacent to the category rather than a pure play. Every row shows the company's own description and its RevenueBase Smart Search rating so you can judge each match yourself. Read the full methodology: how the lists are built, how the judging worked, and what the figure means.
Ranking: Team size, largest first: companies are ordered by the number of professionals RevenueBase tracks at each one. Employee ranges shown are reported bands, for context.
Verification: Every listed company carries at least one verified work email, 1,309 across the full list. Contacts re-verify on a rolling cadence, and each contact's own verification date is shown inside RevenueBase.
Refresh: This page's figures were pulled from the company graph on September 19, 2026. Lists refresh periodically as the graph is re-checked.
Corrections: Wrong category, wrong headquarters, or a company that has closed? Use “Report an issue” on any row. Reports go to the RevenueBase Data Team and feed back into the company graph.

Environmental advocacy organizations by metro in the United States

Environmental advocacy organizations in Washington76
Environmental advocacy organizations in New York31
Environmental advocacy organizations in San Francisco28
Environmental advocacy organizations in Seattle28

Frequently asked

What is RevenueBase Smart Search?

RevenueBase Smart Search is how RevenueBase decides which companies belong on this list and how strongly each one fits. Its data engine and AI assess a company's LinkedIn profile, information supplied directly by the company, its website and other publicly available information, then relate it to the category the list is about. Each row is rated strong evidence when the company's own description names environmental advocacy organizations, partial evidence when it names part of the category, and indirect evidence when the description shown names none of it and the match rests on the rest of the company's profile.

How many environmental advocacy organizations are there based in Washington, United States?

RevenueBase identified 76 environmental advocacy organizations headquartered in Washington, United States as of September 2026, matched on each company's own description of what it does rather than its industry code.

What is the largest company on this list?

Clean Water Action, headquartered in Washington, tops this list with the largest team on record.

Which city has the most environmental advocacy organizations?

Washington leads with 76 headquartered companies, followed by New York (31) and San Francisco (28).

How do I get contact information for these companies?

A free RevenueBase account lets you run this exact search and work the top results, verified emails and direct dials included. Upgrading unlocks all 1,309 verified decision-maker contacts tracked across these 76 companies.

How current is this list?

The list refreshes periodically as the company graph is re-checked. This page's figures were pulled on September 19, 2026.

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About this data

RevenueBase is a B2B data infrastructure company. Its company graph covers 60 million companies and 398.9 million professional contacts, with emails verified on a rolling cadence rather than scraped once and left to decay. These company lists are generated directly from that graph with RevenueBase Smart Search, the same natural-language company search every RevenueBase user has: describe a market in plain words, get the companies that match, and add verified emails and direct dials for the people at them. It is the same data that powers RevenueBase's B2B data products, and a free account includes 500 credits to start. How these lists are built and judged.