More than 740 libraries around the world have chosen to include participation in Portico as one important component of their digital preservation strategy. Early participants are designated Archive Founders and are identified as such in the lists below.
| Libraries | Archive Founders |
|---|---|
| Oakland University | yes |
| Oklahoma State University - Center for Health Sciences | yes |
| Oklahoma State University Institute of Technology | yes |
| Oklahoma State University, Oklahoma City | yes |
| Oklahoma State University, Stillwater | yes |
| Oklahoma State University, Tulsa | yes |
| Old Dominion University | yes |
| Open University of Cyprus | |
| Open University of Greece | yes |
| Open University of Israel | |
| Open University, UK | |
| Oregon Health & Science University | yes |
| Oswaldo Cruz Foundation |