An increasing understanding of the etiology, course, prevention, and treatment of substance use disorders and their related harms continues apace, aided by multidisciplinary research efforts and new discoveries and technologies in a range of allied scientific disciplines. In this concluding chapter of The Oxford Handbook of Substance Use and Substance Use Disorders, the authors highlight a range of opportunities and challenges facing those interested in gaining a basic understanding of the nature of these phenomena and the novel approaches emerging to assess, prevent, and treat these conditions with the goal of reducing the enormous burden these problems place on individuals, families, communities, and our global society as a whole.