- Siree Jankalyan Seva Trast, Badoli
- SIRI – Society for Inspiring Reasearch and Innovation, Warangal
- Siri Rural Development Society, Bidar
- SIRI, Guntur
- SIRI, Srikakulam
- Sirwani Foundation Trust, New Delhi
- SISD – Sanchar Integrated Social Development, New Delhi
- Sishmon Charity Foundation, Barasat
- Sister Margaret Foundation, Kolkata
- Sisters of Charity of St. Anne, Kheda
- Sisu ‘O’ Mahila Kalyan Samiti, Malkangiri
- Sita Gramoudyog Vikas Sansthan, Patna
- Sitamarhi Lok Seva Sansthan
- SITAR, Dharamapuri
- Sitara Swayamsevi Sanstha, Delhi
- SIVA – Service Initiative for Voluntary Action Trust, Tirunelveli
- Siva Baba Urban and Rural Development Society, Kurnool
- Siva Prasad Memorial Trust, Hyderabad
- Siva Sakati Jan Sampark Samiti, Mau
- Siva Youth Society, Nellore
- Sivalayam Edcuational Institutions Trust, Coimbatore
- Sivananda Rehabilitation Home, Hyderabad
- Sivasakthi Muthiyor Illam, Thiruvottiyur
- SIWA – Sumila Institute & Welfare Association, Ghazipur
- Sixteen Jewels Social Organization, Agarpara
- Sixty Plus Welfare Association, Mumbai
- Siyon Multipurpose Education Society, Amravati
- Sizak Foundation, Jaipur
- SKCNESC Trust, Vellore
- Skech Trust, Ramanathapuram
- Skenterprises, Chennai
- SKGVS – Sucheta Kripalani Gram Vikas Sansthan, Jodhpur
- SKR Pupil’s Welfare Society, Chimakurthy
- Sks Trust, Salem
- Sky Empowerment Society, Anantapur
- Sky Foundation, Kancheepuram
- SKY Foundation, Mumbai
- Sky India Foundation, Lucknow
- Skylark Community Development Society, Mattiphata Bajar
- Skylark Education Welfare Society, New Delhi
- Skyline Training & Awareness Organization, Veerabhadrapuram
- SLNDS, Malkangiri
- Slnss Trust, Thiruturaipoondi
- Slum Children Educational & Development Trust, New Delhi
- Slum Development Society, Chennai
- Slum Rehabilitation Society, Mumbai
- SM World – Social Mission World, Jagatsinghpur
- Smajik Seva Sansthan, Madhubani
- Small Wonders School, Patna
- SMARD – Society for Modern Approach of Rural Development, Nagappatinam
