| Congressional Black Caucus FoundationEIN 52-1160561 | Research and Public Policy | DC | $7,300,039Mid-sized | 89.01 |
| Congressional Medal of Honor FoundationEIN 25-1828488 | Human and Civil Rights | VA | $4,580,569Mid-sized | 100.00 |
| Congressional Sportsmen's FoundationEIN 52-1686163 | Animals | DC | $4,450,193Mid-sized | 78.44 |
| ConnCANEIN 20-1612161 | Education | CT | $2,013,054Small | 76.38 |
| Connect2Help 2-1-1EIN 31-1216792 | Human Services | IN | $2,490,328Small | 88.76 |
| Connecticut Association for Human ServicesEIN 06-0653158 | Research and Public Policy | CT | $1,624,056Small | 86.93 |
| Connecticut Audubon SocietyEIN 06-0653531 | Environment | CT | $3,731,785Mid-sized | 94.19 |
| Connecticut Cancer FoundationEIN 06-1240574 | Health | CT | $942,787Small | 88.74 |
| Connecticut Food BankEIN 06-1063025 | Human Services | CT | $48,839,774Large | 91.03 |
| Connecticut Fund for the EnvironmentEIN 06-0990195 | Environment | CT | $3,663,406Mid-sized | 92.37 |
| Connecticut Historical SocietyEIN 06-6026012 | Arts, Culture, Humanities | CT | $3,041,718Small | 85.24 |
| Connecticut Humane SocietyEIN 06-0667605 | Animals | CT | $8,990,903Mid-sized | 89.17 |
| Connecticut LandmarksEIN 06-0789151 | Arts, Culture, Humanities | CT | $1,955,963Small | 90.31 |
| Connecticut Legal ServicesEIN 06-0955461 | Human and Civil Rights | CT | $11,944,323Mid-sized | 79.00 |
| Connecticut Public BroadcastingEIN 06-0758938 | Arts, Culture, Humanities | CT | $22,123,694Large | 85.22 |
| Connecticut Voices for ChildrenEIN 06-1435280 | Human Services | CT | $1,151,496Small | 90.86 |
| Connections for Abused Women and their ChildrenEIN 36-2950380 | Human Services | IL | $1,833,855Small | 94.58 |
| Connie Maxwell Children's HomeEIN 57-0324927 | Human Services | SC | $9,553,199Mid-sized | 87.85 |
| Conquer Cancer Foundation of the American Society of Clinical OncologyEIN 31-1667995 | Health | VA | $27,245,874Large | 95.85 |
| 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 |
| Consortium for Graduate Study in ManagementEIN 43-0962198 | Education | MO | $36,743,080Large | 84.82 |
| Constitutional Accountability CenterEIN 52-2063854 | Research and Public Policy | DC | $3,469,685Small | 91.86 |
| Constitutional Rights FoundationEIN 95-2219680 | Education | CA | $1,944,718Small | 86.71 |
| Contemplative OutreachEIN 13-3345685 | Religion | NJ | $864,788Small | 80.86 |
| Contemporary Art Museum St. LouisEIN 43-1202816 | Arts, Culture, Humanities | MO | $2,732,507Small | 91.49 |
| Contemporary Arts Center, CincinnatiEIN 31-0590095 | Arts, Culture, Humanities | OH | $4,498,292Mid-sized | 84.87 |
| Contemporary Arts Center, New OrleansEIN 72-0798830 | Arts, Culture, Humanities | LA | $3,623,733Mid-sized | 87.95 |
| Contemporary Arts Museum HoustonEIN 74-1093771 | Arts, Culture, Humanities | TX | $2,751,030Small | 83.77 |
| Contemporary Jewish MuseumEIN 47-0920831 | Arts, Culture, Humanities | CA | $10,845,438Mid-sized | 76.22 |
| Continental Baptist MissionsEIN 38-1398829 | Religion | MI | $2,527,365Small | 74.84 |
| Convalescent Aid SocietyEIN 95-1782304 | Health | CA | $1,081,202Small | 88.51 |
| Convoy of HopeEIN 68-0051386 | Human Services | MO | $157,932,066Large | 96.46 |
| Cookie CartEIN 41-1866804 | Human Services | MN | $1,819,163Small | 86.99 |
| Cookson Hills Christian SchoolEIN 73-0665495 | Human Services | OK | $2,958,651Small | 92.26 |
| Cool GirlsEIN 58-1958246 | Human Services | GA | $557,843Small | 81.93 |
| Cooperative for EducationEIN 31-1545464 | International | OH | $3,509,251Mid-sized | 91.38 |
| Copperhead CharitiesEIN 59-2319162 | Human Services | FL | $11,761,740Mid-sized | 67.37 |
| Coptic OrphansEIN 54-1637257 | International | VA | $7,447,158Mid-sized | 93.15 |
| Coral Reef AllianceEIN 94-3211245 | Environment | CA | $3,119,480Small | 92.03 |
| Cornerstone Assistance NetworkEIN 75-2417646 | Human Services | TX | $3,311,773Small | 94.79 |
| Cornerstone Schools AssociationEIN 38-2995984 | Education | MI | $7,238,576Mid-sized | 82.97 |
| Cornerstone Schools of AlabamaEIN 63-0948472 | Education | AL | $4,720,180Mid-sized | 77.92 |
| Cornerstone TeleVisionEIN 23-7112560 | Religion | PA | $5,988,333Mid-sized | 73.71 |
| Cornerstone Theater CompanyEIN 95-4493498 | Arts, Culture, Humanities | CA | $1,289,866Small | 86.04 |
| Cornucopia Institute IncorporatedEIN 20-1075143 | Education | WI | $937,760Small | 94.57 |
| Coro New York Leadership CenterEIN 13-3571610 | Education | NY | $2,587,498Small | 87.70 |
| Coro Northern CaliforniaEIN 94-3117758 | Education | CA | $1,502,444Small | 83.85 |
| Corporate AccountabilityEIN 41-1322686 | Human and Civil Rights | MA | $6,385,613Mid-sized | 93.30 |
| Corporation for Jefferson's Poplar ForestEIN 54-1258296 | Arts, Culture, Humanities | VA | $2,013,364Small | 79.80 |
| Corporation for Supportive HousingEIN 13-3600232 | Community Development | NY | $38,140,011Large | 94.67 |
| Correctional Peace Officers FoundationEIN 68-0023302 | Human Services | CA | $8,090,088Mid-sized | 86.30 |