| Center for Creative Land RecyclingEIN 94-3302410 | Environment | CA | $984,006Small | 89.40 |
| Center for EcoliteracyEIN 94-2911417 | Environment | CA | $2,386,398Small | 88.26 |
| Center for Energy Efficiency and Renewable TechnologiesEIN 68-0260751 | Environment | CA | $2,329,330Small | 81.32 |
| Center for International Environmental LawEIN 52-1633220 | Environment | DC | $2,606,242Small | 96.20 |
| Center for Neighborhood TechnologyEIN 36-2967283 | Environment | IL | $4,290,326Mid-sized | 71.62 |
| Central Park ConservancyEIN 13-3022855 | Environment | NY | $72,425,618Large | 94.20 |
| CeresEIN 22-3053747 | Environment | MA | $14,937,631Large | 96.52 |
| Charles River Watershed AssociationEIN 04-6136989 | Environment | MA | $1,159,643Small | 76.43 |
| Chattahoochee RiverkeeperEIN 58-2095413 | Environment | GA | $2,483,987Small | 95.05 |
| Chesapeake Bay TrustEIN 52-1454182 | Environment | MD | $12,114,935Mid-sized | 97.23 |
| Chesapeake Climate Action NetworkEIN 11-3644283 | Environment | MD | $1,350,959Small | 91.29 |
| Chesapeake ConservancyEIN 26-2271377 | Environment | MD | $4,045,632Mid-sized | 97.13 |
| Chicago Botanic GardenEIN 36-2225482 | Environment | IL | $48,755,048Large | 88.85 |
| Chicago Gateway GreenEIN 36-3764084 | Environment | IL | $618,570Small | 82.05 |
| Cibolo Nature Center & FarmEIN 74-2564700 | Environment | TX | $3,672,517Mid-sized | 85.33 |
| Cincinnati Nature CenterEIN 31-6057978 | Environment | OH | $4,653,544Mid-sized | 77.13 |
| Cincinnati Parks FoundationEIN 31-1429016 | Environment | OH | $1,059,563Small | 89.02 |
| City Parks FoundationEIN 13-3561657 | Environment | NY | $20,273,100Large | 94.26 |
| Civic Garden Center of Greater CincinnatiEIN 31-0559893 | Environment | OH | $779,757Small | 79.83 |
| Clean Ocean ActionEIN 22-2897204 | Environment | NJ | $581,461Small | 92.82 |
| Clean Water FundEIN 52-1043444 | Environment | DC | $5,390,587Mid-sized | 90.03 |
| Clean WisconsinEIN 39-1413448 | Environment | WI | $1,905,696Small | 89.72 |
| Cleveland Botanical GardenEIN 34-0239538 | Environment | OH | $7,054,254Mid-sized | 72.19 |
| Climate CentralEIN 26-1797336 | Environment | NJ | $9,872,125Mid-sized | 84.53 |
| Climate SolutionsEIN 91-1123302 | Environment | WA | $3,134,433Small | 82.66 |
| Coalition for Clean AirEIN 23-7120567 | Environment | CA | $1,050,597Small | 85.15 |
| Coalition to Restore Coastal LouisianaEIN 72-1115589 | Environment | LA | $2,240,672Small | 85.48 |
| Coastal Conservation AssociationEIN 74-1984482 | Environment | TX | $13,776,533Large | 81.37 |
| Coastal Conservation LeagueEIN 57-0887278 | Environment | SC | $3,691,863Mid-sized | 91.84 |
| Coastal Maine Botanical GardensEIN 01-0476545 | Environment | ME | $4,847,073Mid-sized | 85.71 |
| Coming CleanEIN 04-3429794 | Environment | VT | $984,122Small | 82.69 |
| Committee For A Constructive TomorrowEIN 52-1462893 | Environment | DC | $1,754,758Small | 70.10 |
| Communities for a Better EnvironmentEIN 94-2998086 | Environment | CA | $2,066,472Small | 83.88 |
| Community Environmental CouncilEIN 94-1728064 | Environment | CA | $1,225,334Small | 87.24 |
| Connecticut Audubon SocietyEIN 06-0653531 | Environment | CT | $3,731,785Mid-sized | 94.19 |
| Connecticut Fund for the EnvironmentEIN 06-0990195 | Environment | CT | $3,663,406Mid-sized | 92.37 |
| Conservancy for Cuyahoga Valley National ParkEIN 34-1917257 | Environment | OH | $4,242,928Mid-sized | 88.91 |
| Conservancy of Southwest FloridaEIN 59-1157084 | Environment | FL | $8,102,079Mid-sized | 93.89 |
| Conservation Colorado Education FundEIN 84-0614285 | Environment | CO | $1,902,201Small | 92.20 |
| Conservation Foundation of the Gulf CoastEIN 20-0345249 | Environment | FL | $1,097,099Small | 95.85 |
| Conservation InternationalEIN 52-1497470 | Environment | VA | $149,806,220Large | 95.88 |
| Conservation Lands FoundationEIN 20-8924520 | Environment | CO | $7,028,672Mid-sized | 94.33 |
| Conservation Law FoundationEIN 04-6149986 | Environment | MA | $9,439,409Mid-sized | 91.21 |
| Conservation MinnesotaEIN 41-2017329 | Environment | MN | $1,455,520Small | 88.06 |
| Conservation NorthwestEIN 94-3091547 | Environment | WA | $2,055,902Small | 87.29 |
| Conservation Strategy FundEIN 94-3294843 | Environment | DC | $2,079,533Small | 87.92 |
| Coral Reef AllianceEIN 94-3211245 | Environment | CA | $3,119,480Small | 92.03 |
| Cultural Landscape FoundationEIN 52-2092229 | Environment | DC | $1,301,543Small | 86.63 |
| Delaware Nature SocietyEIN 51-6018321 | Environment | DE | $4,326,285Mid-sized | 91.54 |
| Delaware Riverkeeper NetworkEIN 74-3255972 | Environment | PA | $2,931,825Small | 88.44 |
| Denison Pequotsepos Nature CenterEIN 06-0884024 | Environment | CT | $1,362,888Small | 76.92 |
| Denver Botanic GardensEIN 84-0440359 | Environment | CO | $21,365,255Large | 90.84 |
| Descanso Gardens Guild, Inc.EIN 95-2511202 | Environment | CA | $8,740,038Mid-sized | 89.78 |
| Desert Botanical GardenEIN 86-0136925 | Environment | AZ | $15,606,893Large | 83.88 |
| Discovery Green ConservancyEIN 20-1951465 | Environment | TX | $7,362,363Mid-sized | 94.07 |
| Dogwood AllianceEIN 56-2139120 | Environment | NC | $1,552,587Small | 88.31 |
| Earth Conservation CorpsEIN 52-1683270 | Environment | DC | $350,700Small | 74.09 |
| Earth Day NetworkEIN 13-3798288 | Environment | DC | $2,970,282Small | 91.94 |
| Earth ForceEIN 52-1830873 | Environment | CO | $1,002,263Small | 84.00 |
| Earth Island InstituteEIN 94-2889684 | Environment | CA | $9,751,020Mid-sized | 88.24 |