School of Social Work is the oldest and the largest division at the NISD. It conducts Professional Degrees in Social Work. It has got the highest number of post graduate level qualified Social Work academics in the country at present. 

At present the School of Social Work conducts following academic programmes of the institute. They are;

• Master Degree programme in Social Work (2 year, Weekend, English medium)
• Bachelor's Degree programme in Social Work (4 year, Weekday, English medium)
• Higher Diploma programme in Social Work (2 year, Weekday, Sinhala, Tamil & English medium)
• Diploma programme in Social Work (1 year, Weekday & Weekend, Sinhala, Tamil & English medium)
• Diploma in Women Empowerment (1 year, Weekend, Sinhala & Tamil medium)
• Diploma in Sign Language Interpretation (1 year, Weekend, Sinhala medium)

School of Social Work is the predecessor of the National Institute of Social Development. It was established in 1952 under the name Institute of Social Work, as a non-governmental organization. It was named as the Ceylon School of Social Work in 1964 when it became a government institution. The School was renamed as the Sri Lanka School of Social Work in 1972. In order to offer under graduate and post graduate degrees in Social Work the School was brought under the National Institute of Social Development, an independent institute established on the recommendation of the University Grants Commission.