As an occupational therapist (OT), per diem jobs are those positions that allow you to work daily or as-needed for an employer. In this role, you may provide OT services to patients during your shift, perform assessments of their needs to help full-time therapists, and coordinate with caregivers. This job is sometimes advertised as PRN, which stands for "pro re nata" and simply means working as needed. Per diem occupational therapists may substitute for other therapists who are sick or on vacation, help fill in staffing shortages, or travel between different clinics within a predetermined area. Some per diem occupational therapists specialize in specific types of problems and focus on complicated issues, allowing regular staff to attend to more common ailments.