Company lists · Data refreshed September 2026

Top 25 Environmental research and advocacy organizations based in the United States

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

Compiled by the RevenueBase Data Team Data refreshed Sep 19, 2026 1,865 companies tracked

RevenueBase identified 1,865 environmental research and advocacy organizations headquartered in the United States as of September 2026 and tracks 44,481 professional contacts across them, including 17,505 with verified work emails. Washington is the largest hub.

This list covers environmental research and advocacy organizations headquartered in the 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

1,865Companies

44,481Contacts tracked

17,505Verified emails

Explore this list → Free signup · no credit card · 500 free credits

The 25 largest environmental research and advocacy organizations based in the United States

Ranked by team size

Top 25 of 1,865 environmental research and advocacy organizations based in the 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 research and 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	The Nature Conservancy	Indirect evidence	Arlington, VA, United StatesHQ checked Sep 19, 2026	5,001-10,000	6,526 contacts →
	Indirect evidence “Air, water, food, shelter, income: nature sustains every aspect of our lives.” Source: RevenueBase Database · checked Sep 19, 2026
2	Conservation International	Indirect evidence	Arlington, VA, United StatesHQ checked Sep 19, 2026	501-1,000	1,560 contacts →
	Indirect evidence “Since 1987, Conservation International has worked to spotlight and secure the critical benefits that nature provides to humanity.” Source: RevenueBase Database · checked Sep 19, 2026
3	World Resources Institute	Indirect evidence	Washington, DC, United StatesHQ checked Sep 19, 2026	1,001-5,000	1,359 contacts →
	Indirect evidence “WRI works to improve people’s lives, protect and restore nature and stabilize the climate.” Source: RevenueBase Database · checked Sep 19, 2026
4	Environmental Defense Fund	Partial evidence	New York, NY, United StatesHQ checked Sep 19, 2026	1,001-5,000	1,352 contacts →
	Partial evidence “We are Environmental Defense Fund, a leading environmental nonprofit focused on stabilizing the climate while helping build strong and healthy communities.” Source: RevenueBase Database · checked Sep 19, 2026
5	Sierra Club	Indirect evidence	Oakland, CA, United StatesHQ checked Sep 19, 2026	501-1,000	1,069 contacts →
	Indirect evidence “At the Sierra Club, we believe in the power of togetherness.” Source: RevenueBase Database · checked Sep 19, 2026
6	Natural Resources Defense Council Nrdc	Partial evidence	New York, NY, United StatesHQ checked Sep 19, 2026	501-1,000	942 contacts →
	Partial evidence “NRDC is the nation's most effective environmental action organization.” Source: RevenueBase Database · checked Sep 19, 2026
7	Earthjustice	Indirect evidence	San Francisco, United StatesHQ checked Sep 19, 2026	501-1,000	672 contacts →
	Indirect evidence “Earthjustice is a non-profit public interest law organization dedicated to protecting the magnificent places, natural resources, and wildlife of this earth, and to defending the…” Source: RevenueBase Database · checked Sep 19, 2026
8	PETA	Indirect evidence	Norfolk, VA, United StatesHQ checked Sep 19, 2026	201-500	592 contacts →
	Indirect evidence “People for the Ethical Treatment of Animals (PETA) entities have more than 10.4 million members and supporters globally, and PETA U.S.” Source: RevenueBase Database · checked Sep 19, 2026
9	Mass Audubon	Indirect evidence	Lincoln, MA, United StatesHQ checked Sep 19, 2026	201-500	554 contacts →
	Indirect evidence “Mass Audubon is the largest nature-based conservation organization in New England.” Source: RevenueBase Database · checked Sep 19, 2026
10	Western Ecosystems Technology, Inc. West	Strong evidence	Cheyenne, WY, United StatesHQ checked Sep 19, 2026	201-500	408 contacts →
	Strong evidence “WEST provides environmental and statistical consulting services and contract research nationally and internationally to industry, government, and private organizations.” Source: RevenueBase Database · checked Sep 19, 2026
11	RARE	Indirect evidence	Arlington, VA, United StatesHQ checked Sep 19, 2026	51-200	368 contacts →
	Indirect evidence “Rare is a global leader in driving social change for people and nature.” Source: RevenueBase Database · checked Sep 19, 2026
12	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
13	Lynker	Partial evidence	Leesburg, VA, United StatesHQ checked Sep 19, 2026	501-1,000	363 contacts →
	Partial evidence “Lynker delivers innovative solutions to support global environmental security and economic prosperity as a trusted partner to governments, communities, and industry.” Source: RevenueBase Database · checked Sep 19, 2026
14	Chesapeake BAY Foundation	Indirect evidence	Annapolis, MD, United StatesHQ checked Sep 19, 2026	51-200	312 contacts →
	Indirect evidence “The Chesapeake Bay Foundation (CBF) fights for bold and creative solutions to the pollution that plagues the Bay and its tributaries.” Source: RevenueBase Database · checked Sep 19, 2026
15	GSI Environmental INC	Partial evidence	Houston, TX, United StatesHQ checked Sep 19, 2026	201-500	259 contacts →
	Partial evidence “GSI Environmental, Inc.(GSI), is an environmental engineering and science consulting firm committed to measuring, analyzing, and solving complex environmental problems around the…” Source: RevenueBase Database · checked Sep 19, 2026
16	Union Of Concerned Scientists	Indirect evidence	Cambridge, MA, United StatesHQ checked Sep 19, 2026	201-500	254 contacts →
	Indirect evidence “Our mission is to use rigorous, independent science to solve our planet's most pressing problems.” Source: RevenueBase Database · checked Sep 19, 2026
17	Ceres, INC	Partial evidence	Boston, MA, United StatesHQ checked Sep 19, 2026	51-200	241 contacts →
	Partial evidence “Ceres is a nonprofit advocacy organization working to accelerate the transition to a cleaner, more just, and resilient world.” Source: RevenueBase Database · checked Sep 19, 2026
18	Seaside Sustainability	Partial evidence	Gloucester, MA, United StatesHQ checked Sep 19, 2026	51-200	240 contacts →
	Partial evidence “Seaside Sustainability is a nationally recognized, award-winning 501(c)3 charitable organization dedicated to community engagement, education and environmental conservation.” Source: RevenueBase Database · checked Sep 19, 2026
19	The Conservation Fund	Indirect evidence	Arlington, VA, United StatesHQ checked Sep 19, 2026	201-500	224 contacts →
	Indirect evidence “We are in the business of conservation, creating innovative solutions that drive nature-based action for climate protection, sustainable economies and vibrant communities.” Source: RevenueBase Database · checked Sep 19, 2026
20	Center For Biological Diversity	Indirect evidence	Tucson, AZ, United StatesHQ checked Sep 19, 2026	51-200	219 contacts →
	Indirect evidence “At the Center for Biological Diversity, we believe that the welfare of human beings is deeply linked to nature, to the existence in our world of a vast diversity of wild animals…” Source: RevenueBase Database · checked Sep 19, 2026
21	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
22	Energy & Environmental Research Center	Strong evidence	Grand Forks, ND, United StatesHQ checked Sep 19, 2026	201-500	213 contacts →
	Strong evidence “The Energy & Environmental Research Center (EERC) is recognized as one of the world's leading developers of cleaner, more efficient energy to power the world and environmental…” Source: RevenueBase Database · checked Sep 19, 2026
23	Conservation Corps Minnesota & Iowa	Partial evidence	St. Paul, MN, United StatesHQ checked Sep 19, 2026	201-500	207 contacts →
	Partial evidence “At Conservation Corps Minnesota & Iowa, youth and young adults grow as environmental stewards and leaders while giving back to the community through meaningful service.” Source: RevenueBase Database · checked Sep 19, 2026
24	Defenders Of Wildlife	Indirect evidence	Washington, DC, United StatesHQ checked Sep 19, 2026	51-200	202 contacts →
	Indirect evidence “Defenders of Wildlife is dedicated to the protection of all native animals and plants in their natural communities.” Source: RevenueBase Database · checked Sep 19, 2026
25	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

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 research and 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 research and advocacy organizations.
Partial evidence: Its own public description names part of environmental research and 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 research and 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 1,865 environmental research and advocacy organizations based in the United States

See the full list, filter by size, metro and specialty, and get verified emails and direct dials for all 17,505 reachable decision-makers.

Free signup · no credit card

View the full list →

Environmental research and advocacy organizations based in the United States at a glance

As of Sep 19, 2026

39.4%Verified-email coverage

23.9Average contacts per company

1-10Median size (employees)

6.3%Largest-city concentration · Washington

Sep 19, 2026Page data refreshed

Companies by employee count

1-10

1,184

11-50

505

51-200

117

201-500

501-1,000

1,001-5,000

5,001-10,000

10001+

Email recency for this list is measured worldwide rather than for United States, so it is reported there. Company counts and contact totals on this page are exact for United States, over 1,865 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 research and 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 the United States whose own description of what they do matches “environmental research and 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 research and 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 research and advocacy organizations, and records with no verified work email. Companies headquartered outside United States 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, 17,505 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 research and advocacy organizations by metro

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 research and 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 research and advocacy organizations are there based in the United States?

RevenueBase identified 1,865 environmental research and advocacy organizations headquartered in the 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?

The Nature Conservancy, headquartered in Arlington, tops this list with the largest team on record.

Which city has the most environmental research and advocacy organizations?

Washington leads with 118 headquartered companies, followed by New York (67) and San Francisco (42).

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 17,505 verified decision-maker contacts tracked across these 1,865 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.

Ready to reach these companies? Verified emails and direct dials for all 1,865 environmental research and advocacy organizations based in the United States. Start with a free account, no credit card.

Download this list →

Related lists

Environmental research and advocacy organizations by geography

Browse the directory

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.