| Sadleir House Library | Peterborough |
| Saint Joseph's at Fleming | Peterborough |
| Salvation Army, Christmas Food Assistance and Toy Shop, Peterborough - Simcoe St | Peterborough |
| Salvation Army, Community and Family Services, Peterborough - Simcoe St | Peterborough |
| Salvation Army, Correctional and Justice Services, Anger and Conflict Management Program, Peterborough - Simcoe St | Peterborough |
| Salvation Army, Correctional and Justice Services, Peterborough - Simcoe St | Peterborough |
| SE Health, Central East Office | Whitby |
| Selwyn Outreach Centre, FRIENDS Peterborough | Peterborough |
| Selwyn Outreach Centre | Selwyn Township |
| Selwyn Public Library, Bridgenorth Branch | Selwyn Township |
| Selwyn Public Library, Ennismore Branch | Selwyn Township |
| Selwyn Public Library, Lakefield Branch | Selwyn Township |
| Selwyn. Municipal Office, Bridgenorth, Selwyn Fire Department | Selwyn Township |
| Senior Lunch Club, No Physical Location | Peterborough |
| Seniors Dreams, Peterborough | Peterborough |
| Service Canada, Peterborough, Service Canada Centre | Peterborough |
| ServiceOntario | Toronto |
| ServiceOntario, Lakefield, Lakefield Service Counter | Lakefield |
| ServiceOntario, Millbrook, Millbrook Service Counter | Cavan Monaghan |
| ServiceOntario, Norwood, Norwood Service Counter | Norwood |
| ServiceOntario, Office of the Registrar General | Toronto |
| ServiceOntario, Peterborough Land Registry Office 45, Peterborough | Peterborough |
| ServiceOntario, Peterborough, Peterborough Service Counter | Peterborough |
| Sherbrooke Heights Retirement, Sherbrooke Heights | Peterborough |
| Shopease Foods Inc | Peterborough |
| Showplace Performance Centre | Peterborough |
| Sikh Fellowship, Peterborough | Peterborough |
| Silver Cross | Oshawa |
| Smith Ennismore Historical Society | Selwyn Township |
| Sobey's, Peterborough - Towerhill | Peterborough |
| Society for Creative Anachronism, The Canton of Petrea Thule | Peterborough |
| Society of Saint Vincent de Paul, Lakefield - Queen St, Vinnie's Feel Good Shopping | Selwyn Township |
| Society of Saint Vincent de Paul, Peterborough - Hunter St E, Vinnie's Feel Good Shopping | Peterborough |
| Society of Saint Vincent de Paul, Peterborough - Murray St, Food Pantry | Peterborough |
| Special Olympics Ontario - Central Ontario, Peterborough - No Physical Address, Special Olympics Ontario - Peterborough Chapter | Peterborough |
| Spinal Cord Injury Ontario [Central East], Warsaw - Mailing Address, Peterborough Regional Office | Douro-Dummer |
| St John Ambulance, Peterborough | Peterborough |
| St John's Retirement Homes | Peterborough |
| St Leonard's Society of Peterborough, Edmison House Community Residential Facility | Peterborough |
| St Luke's Anglican Church, Peterborough | Peterborough |
| St Stephen's Presbyterian Church, Peterborough | Peterborough |
| St. Giles Senior Citizens Residence | Peterborough |
| St. John the Baptist Anglican Church, Lakefield | Selwyn Township |
| St.James Players, St James Players | Peterborough |
| Stewart Homes | Peterborough |
| Studio 201 | Peterborough |
| Summit Terrace Luxury Senior Apartments | Peterborough |
| Survivors Abreast Dragon Boat Team | Peterborough |
| Sweet Adelines International, Kawartha Music Company Chorus | Peterborough |
