| Clackamas Academy Of Industrial Sciences | Academic & Science |
| Commercial Academic Information Systems | Academic & Science |
| Canadian Association for Information Science | Academic & Science |
| Center for Artificial Intelligence in Society | Academic & Science |
| Campus Advanced Information System | Academic & Science |
| Concordia Administrative Information System | Academic & Science |
| Chemical Agent Identification Set | Academic & Science |
| Credit Account Information Sharing | Accounts and Finance |
| CAIS Internet, Inc. | Business |
| Cayman Alternative Investment Summit | Business |
| Center for Assessment and Instructional Support | Community |
| Canadian Association of Independent Schools | Community |
| California Association of Independent Schools | Community |
| Connecticut Association of Independent Schools | Community |
| Canadian Accredited Independent Schools | Community |
| Communications of the Association for Information Systems | Community |
| Community Advice and Information Service | Community |
| Canadian Association for Irish Studies | Community |
| Common Apse Interface Specification | Computing |
| Collocated Automatic Intercept System | Computing |
| Circle of Ancient Iranian Studies | General |
| Correctional Assessment and Intervention System | General |
| Copper Amino Isolate Serum | General |
| Center For Applied Isotope Studies | General |
| Central American Integration System | General |
| Condition Assessment Information System | General |
| Cartilage Autograft Implantation System | General |
| Context Awareness Information Services | General |
| California Accountability and Improvement System | General |
| CA Accountability and Improvement System | General |
| Condensed Abbreviated Injury Scaling | General |
| Car Area Information Sensing | General |
| Credit Application Information Sharing | General |
| Cold Air Induction System | General |
| Cold Air Intake System | General |
| Certified Automotive Information Specialist | General |
| Contact Area Information Sensing | General |
| Canadian Agricultural Income Stabilization | General |
| Caribbean Agricultural Information Service | General |
| Certified agricultural irrigation specialists | General |
| Childhood Agricultural Injury Survey | General |
| Certified Agricultural Irrigation Specialist | General |
| Central Assessment Information System | Governmental |
| Changchun American International School | International |
| Christian Alliance International School | International |
| Chinese American International School | International |
| Capitol Area Internet Service | Internet |
| Center for Advanced Internet Studies | Internet |
| Cancer Agency Information System | Medical |
| Complete androgen insensitivity syndrome | Medical |
| Common Apse Interface Set | Military and Defence |
