| Champaign County Humane Society | Academic & Science |
| Clark County Humane Society | Academic & Science |
| College of Community Health Sciences | Academic & Science |
| Chester County Historical Society | Academic & Science |
| Copper Country Humane Society | Academic & Science |
| Camden County High School | Academic & Science |
| College and Career High School | Business |
| Cape Coral High School | Community |
| Central Crossing High School | Community |
| Currie Community High School | Community |
| Charleston Catholic High School | Community |
| Cypress Creek High School | Community |
| Cherry Creek High School | Community |
| Christopher Columbus High School | Community |
| Corydon Central High School | Community |
| Carroll County High School | Community |
| Culver City High School | Community |
| Columbia City High School | Community |
| Calvary Christian High School | Community |
| Cesar Chavez High School | Community |
| Cathedral Catholic High School | Community |
| Carmel Catholic High School | Community |
| Carbondale Community High School | Community |
| Coal City High School | Community |
| Clear Creek High School | Community |
| Corner Canyon High School | Community |
| Copperas Cove High School | Community |
| Cathedral City High School | Community |
| Carver Christian High School | Community |
| Chatsmore Catholic High School | Community |
| Chicago Christian High School | Community |
| Chicopee Comprehensive High School | Community |
| Codsall Community High School | Community |
| Clarke Central High School | Community |
| Camden Catholic High School | Community |
| Cañon City High School | Community |
| Clay-Chalkville High School | Community |
| Central Cabarrus High School | Community |
| Charlotte Catholic High School | Community |
| Communitas Charter High School | Community |
| Concord-Carlisle High School | Community |
| Conley-Caraballo High School | Community |
| Copper Canyon High School | Community |
| Covenant Christian High School | Community |
| Covington Catholic High School | Community |
| Cross Creek High School | Community |
| Culver Community High School | Community |
| Central Catholic High School | Community |
| Catholic Central High School | Community |
| Computerized Criminal History System | Computing |
| Cross Country Home Services | General |
| Contra Costa | General |
| Columbus Center For Human Services | General |
| Contra Costa Health Services | Medical |
| Christiana Care Health System | Medical |
| Congenital central hypoventilation syndrome | Medical |
| Congental Central Hypoventilation Syndrome | Medical |
| Childrens Care Hospital And School | Medical |
| Canadian Community Health Survey | Regional |
| Carleton County Historical Society | Regional |
| Columbia County Historical Society | Regional |
| Chelmsford County High School | Regional |
| Clacton County High School | Regional |
| Chilton County High School | Regional |
| Colchester County High School | Regional |
| Clarke County High School | Regional |
| Colleton County High School | Regional |
| Colquitt County High School | Regional |
| Culpeper County High School | Regional |
| Campbell County High School | Regional |
