- SIHA DEVELOPMENT ORGANIZATION
- SINGIDA RURAL PEOPLE LIVING WITH HIV/AIDS(SIRUPHA)
- Small Miners Development Initiatives (SMDI)
- SMS Verification
- Social and Economic Development Foundation (SEDEF)
- SOCIAL MOMENTUM ORGANIZATION
- Social Vision Group Tanzania (SOVIGOTA)
- Society for Women and AIDS in Africa
- Songambele Initiative Organisation
- Southern Africa Human Rights NGOs Network Tanzania Chapter