- SAMIKSHANI, Kolkata
- Sampark Communication, Kolkata
- Samvriddhi Trust, Kolkata
- SAMVRIDDHI, Kolkata
- Sanatan Yoga Kendra, Kolkata
- Sanchar Arod, Kolkata
- Sane & Enthusiast Volunteers Association of Kolkata
- SANHITA, Kolkata
- Sanjib Roy Memorial Trust, Kolkata
- SANLAAP, Kolkata
- SARANI – Society for Action on Rehabilitation Awareness Networking and Information, Kolkata
- SARC – Survey Advisory Research Consultancy, Kolkata
- Saroj Nalini Dutt Memorial Association, Kolkata
- Sasha Association for Craft Producers, Kolkata
- Sathihath Batana, Kolkata
- SAVE – Society Against Violence in Education, Kolkata
- Save the Children Committee of India, Kolkata
- Save The Environment, Kolkata
- SAVIOUR, Kolkata
- SBMS – Seth Bagan Mahila Sangha, Kolkata
- SCHEEM, Kolkata
- School of Human Genetics & Population Health, Kolkata
- Science Communicators Forum, Kolkata
- SCOPE – Socio Cultural Organisation to Promote Equality, Kolkata
- Seva Dharti, Kolkata
- Sharda Devi Nevatia Foundation, Kolkata
- Shastri Nagar Path of Human Resource Development, Kolkata
- Shibkalinagar(N) Welfare Society, Kolkata
- Shimul Music Circle, Kolkata
- Shishiralay Women and Children Charitable Welfare Society, Kolkata
- SHOBHANA, Kolkata
- SHRDF – SubhashChandra Human Research & Development Foundation, Kolkata
- Shree Shree Radharaman Welfare Sangha, Kolkata
- SHWAS Foundation – Social Healing Works & Supports Foundation, Kolkata
- Shyamchak Pratibandhi Kalyan Samiti, Kolkata
- Shyamnagar Citizens Society, Kolkata
- Shyamnagar Progati, Kolkata
- SIBANI, Kolkata
- Silence Training Institute, Kolkata
- Sing to Live, Kolkata
- Sir Syed Group of Schools, Kolkata
- Sister Margaret Foundation, Kolkata
- SMILE – Society Making Impellent Effort, Kolkata
- SNCADA – Subhas Nagar Creative awareness & Development Assosition, Kolkatta
- Social Activity for Gramin Area, Kolkata
- Social Healing Works & Supports Foundation, Kolkata
- Social Organisation for Integrated Living, Kolkata
- Social Synergy, Kolkata
- Society for Direct Initiative for Social and Health Action, Kolkata
- Society for Equitable Voluntary Actions, Kolkata
