Welcome to Module 3 which focuses on public health, harm reduction and treatment. In this Module you will see how public health policies address drug use ; become familiar with various harm reduction concepts and tools and learn a bit about the history as well. You will learn a lot about harm reduction itself, seeing how it can fit into existing health policies and look at how policies can include prevention, harm reduction and treatment in a complementary fashion. By the end of the Module you will be able to : • Recall the concepts and list the tools of harm reduction.• Assess treatment options for dependence• and Explain how prevention, harm reduction and treatment complement each other.We hope this week will provide you with a good sense of what harm reduction is and how it fits within wider public health–oriented policies. This week also builds on what you have learnt in Module 2, with regard to certain health issues and looking at when treatment for dependence may be necessary. Don’t forget to go through the essential reading list and look at the optional additional resources. Best wishes,The Drugs, Drug Use, Drug Policy and Health team