| Indian Law Resource CenterEIN 52-1121079 | Human and Civil Rights | MT | $1,268,568Small | 92.29 |
| Indian Muslim Relief and CharitiesEIN 27-0058132 | International | CA | $5,886,673Mid-sized | 94.74 |
| Indian River Habitat for HumanityEIN 65-0230079 | Community Development | FL | $5,733,247Mid-sized | 92.16 |
| Indiana Black Expo, Inc.EIN 35-1406245 | Community Development | IN | $4,658,463Mid-sized | 78.18 |
| Indiana Historical SocietyEIN 35-0876384 | Arts, Culture, Humanities | IN | $12,091,643Mid-sized | 83.95 |
| Indiana Repertory TheatreEIN 35-1186290 | Arts, Culture, Humanities | IN | $7,233,067Mid-sized | 88.31 |
| Indianapolis Opera CompanyEIN 35-1405179 | Arts, Culture, Humanities | IN | $1,109,270Small | 68.68 |
| Indianapolis Symphony OrchestraEIN 35-0998627 | Arts, Culture, Humanities | IN | $23,290,238Large | 78.59 |
| Indianapolis Urban LeagueEIN 35-6060655 | Human and Civil Rights | IN | $2,226,625Small | 84.04 |
| Indianapolis ZooEIN 35-1074747 | Animals | IN | $32,985,416Large | 88.11 |
| InFaith Community FoundationEIN 41-1802412 | Community Development | MN | $27,770,587Large | 89.55 |
| Infant Crisis ServicesEIN 73-1378766 | Human Services | OK | $3,345,296Small | 92.89 |
| Infant Welfare Society of ChicagoEIN 36-2167752 | Health | IL | $9,544,302Mid-sized | 90.93 |
| Initiative for A Competitive Inner CityEIN 13-3772904 | Community Development | MA | $4,348,578Mid-sized | 97.05 |
| Initiative for Global DevelopmentEIN 20-8003146 | International | DC | $1,036,574Small | 74.91 |
| Initiative FoundationEIN 36-3451562 | Community Development | MN | $7,323,711Mid-sized | 92.11 |
| Inland Empire United WayEIN 33-0502676 | Community Development | CA | $6,839,548Mid-sized | 97.87 |
| INMED Partnerships for ChildrenEIN 52-1482339 | International | VA | $11,283,378Mid-sized | 95.04 |
| Inner City Christian FederationEIN 38-1903026 | Community Development | MI | $3,981,359Mid-sized | 80.42 |
| Inner City Health CenterEIN 74-2426085 | Health | CO | $4,248,776Mid-sized | 85.49 |
| Inner City Law CenterEIN 95-3697572 | Human and Civil Rights | CA | $4,036,319Mid-sized | 93.16 |
| Inner-City ArtsEIN 95-4239478 | Education | CA | $3,939,718Mid-sized | 90.71 |
| Inner-City Scholarship FundEIN 51-0453629 | Education | NY | $17,315,161Large | 88.90 |
| INSIGHTEIN 05-0272278 | Human Services | RI | $848,297Small | 94.37 |
| Insight for LivingEIN 95-3392299 | Religion | TX | $19,580,163Large | 82.54 |
| Inspiration CorporationEIN 36-3673980 | Human Services | IL | $3,630,945Mid-sized | 84.09 |
| Inspire WomenEIN 35-2203762 | Education | TX | $1,006,348Small | 79.22 |
| Institute for Agriculture and Trade PolicyEIN 36-3501938 | Research and Public Policy | MN | $1,790,307Small | 83.92 |
| Institute for America's FutureEIN 52-1971942 | Research and Public Policy | DC | $2,915,846Small | 83.56 |
| Institute for American ValuesEIN 13-3400377 | Research and Public Policy | NY | $626,271Small | 62.30 |
| Institute for Creation ResearchEIN 95-3523177 | Religion | TX | $7,585,130Mid-sized | 93.85 |
| Institute for Educational AdvancementEIN 95-4695698 | Education | CA | $2,150,889Small | 89.48 |
| Institute for Energy ResearchEIN 76-0149778 | Research and Public Policy | DC | $1,666,571Small | 89.48 |
| Institute for Foreign Policy AnalysisEIN 51-0192436 | International | MA | $935,517Small | 63.22 |
| Institute for Free SpeechEIN 20-3676886 | Human and Civil Rights | VA | $1,939,035Small | 97.23 |
| Institute for Global EngagementEIN 23-3042456 | International | VA | $1,479,806Small | 85.85 |
| Institute for Humane StudiesEIN 94-1623852 | Education | VA | $18,238,447Large | 83.65 |
| Institute for JusticeEIN 52-1744337 | Human and Civil Rights | VA | $22,312,263Large | 97.70 |
| Institute for Local Self-RelianceEIN 23-7394104 | Research and Public Policy | DC | $1,525,548Small | 91.75 |
| Institute for Middle East UnderstandingEIN 20-2389388 | International | CA | $1,491,358Small | 85.79 |
| Institute for Policy StudiesEIN 52-0788947 | Research and Public Policy | DC | $3,889,771Mid-sized | 94.21 |
| Institute for Quality EducationEIN 35-1836687 | Education | IN | $9,090,608Mid-sized | 86.44 |
| Institute for the Analysis of Global SecurityEIN 22-3880419 | International | MD | $884,482Small | 60.29 |
| Institute for the Study of WarEIN 26-0273675 | Research and Public Policy | DC | $1,843,667Small | 81.77 |
| Institute for Transportation and Development PolicyEIN 52-1399520 | Environment | NY | $7,664,135Mid-sized | 87.62 |
| Institute for Women's Policy ResearchEIN 52-1549572 | Research and Public Policy | DC | $3,176,103Small | 86.79 |
| Institute of Contemporary Art, Los AngelesEIN 95-3992968 | Arts, Culture, Humanities | CA | $1,286,254Small | 77.28 |
| Institute of International EducationEIN 13-1624046 | International | NY | $358,197,642Large | 83.33 |
| Institute of Noetic SciencesEIN 23-7236986 | Research and Public Policy | CA | $5,024,895Mid-sized | 87.56 |
| Institute of Southern Jewish LifeEIN 64-0762027 | Religion | MS | $2,606,555Small | 75.31 |
| Institute on Religion and Public LifeEIN 52-1628303 | Research and Public Policy | NY | $2,861,837Small | 70.49 |
| Institute on Taxation and Economic PolicyEIN 04-2688165 | Research and Public Policy | DC | $1,804,899Small | 93.91 |
| Inter-Faith Council for Social ServiceEIN 59-1224041 | Human Services | NC | $2,451,180Small | 90.92 |
| Inter-Faith Food ShuttleEIN 56-1753180 | Human Services | NC | $13,594,451Large | 82.98 |
| InterActEIN 58-1320613 | Human Services | NC | $3,155,277Small | 89.26 |
| InterAct MinistriesEIN 92-6004561 | Religion | OR | $2,315,997Small | 84.18 |
| InterActionEIN 13-3287064 | International | DC | $9,733,199Mid-sized | 91.01 |
| Intercollegiate Studies InstituteEIN 23-6050131 | Education | DE | $7,276,782Mid-sized | 94.89 |
| Interface MinistriesEIN 58-1970866 | Religion | GA | $1,206,568Small | 86.94 |
| Interfaith Assistance MinistryEIN 58-1556963 | Human Services | NC | $1,014,698Small | 87.89 |