| Obstetrics and Gynecology, Department of | | | | | | | | |
| Off the Beat | | | | | | | | |
| Off-Campus Services, Office of | | | | | | | | |
| Office of Gift Planning | | | | | | | | |
| Office of Human Research | | | | | | | | |
| Office of Software Licensing | | | | | | | | |
| Office of Student Telephone Services | | | | | | | | |
| Office Relocation Information | | | | | | | | |
| Old Exam File | | | | | | | | |
| Ombudsman, Office of the | | | | | | | | |
| On-Campus Housing (Office of Housing and Conference Services) | | | | | | | | |
| OncoLink®, Penn's cancer resource | | | | | | | | |
| Onda Latina | | | | | | | | |
| Onyx Senior Honor Society | | | | | | | | |
| Open Learning at Penn | | | | | | | | |
| Operations and Information Management Department (OPIM) | | | | | | | | |
| Ophthalmology, Department of | | | | | | | | |
| Organizational Dynamics | | | | | | | | |
| Organizational Dynamics | | | | | | | | |
| Organizational Dynamics Graduate Group | | | | | | | | |
| Orthodox Community at Penn (OCP) | | | | | | | | |
| Orthopaedic Surgery, Department of | | | | | | | | |
| Otorhinolaryngology: Head and Neck Surgery, Department of | | | | | | | | |