NPS provoke new patterns of use and pose unprecedented challenges to (drug) prevention-, careand harm reduction efforts. Similarly, research into drug use needs to reinvigorate and review its practices as well, to address this new situation. At present, data on the epidemiology of NPS are scarcely- and often partially available. Specific knowledge about the use of new substances and the possible health and social impact on users and society, is minimal. Besides the issuing of alerts that involve the use of NPS in the context of European and national Early Warning Systems (EWS), many questions remain. Who uses NPS? How and to which degree? Why? Which substances are popular? What are long-term effects on the health of users? Which specific interventions can we think of? These and other health related issues are tackled by the largely qualitative research endeavour called ‘Understanding New Psychoactive Substance use in Belgium from a health perspective’; in short, the ‘NPS-care’ project. Its findings will contribute to formulate ‘recommendations regarding the organisation and provision of interventions targeting NPS along the continuum of care; from prevention over harm reduction to treatment’ (BELSPO, contract DR/02/79). Data collection covers a two-year period between March 2017 and June 2019. Commissioned and funded by Belgian Federal Science Policy, NPS care was coordinated by the University College of Ghent, joined by Sciensano as co-coordinating partner.