The National Survey on Extent and Pattern of Substance Use in India (also known as the National Drug Use Survey or NDUS) is a large-scale epidemiological study being conducted across the country to estimate the prevalence of use of various psychoactive substances in the Indian population. NDUS involves a combination of several methodological approaches to study the drug use situation in the country which include a general population survey in a representative sample of households throughout India, a Respondent Driven Sampling Survey, Focussed thematic studies and survey among service providers. The survey has been commissioned and funded by the Ministry of Social Justice and Empowerment (MoSJE), Government of India which is the nodal ministry on Drug Demand Reduction. The Ministry of Social Justice and Empowerment has designated National Drug Dependence Treatment Centre (NDDTC), All India Institute of Medical Sciences (AIIMS), New Delhi as the nodal agency for conducting the survey. As the nodal agency, NDDTC, AIIMS has developed the design and methodology for the survey and is responsible for providing technical guidance to the other agencies involved in the project. The survey is being executed as a collaborative project between NDDTC, AIIMS and various Government and Non-governmental Organizations such National Institute of Social Defence (NISD, Government Medical Colleges, Regional Resource and Training Centres (RRTCs) of MoSJE and Integrated Rehabilitation Centres for Addicts (IRCAs). The collaborating agencies are responsible for conducting survey activities in one or more states covered by the NDUS.