This conclusion chapter presents an overview of concepts covered in the preceding chapters of this book. This book presents a selective review of work conducted over the last three decades to advance our understanding of anxiety and anxiety disorders. Several environmental factors of possible importance in the generation of anxiety are detailed in the book, including life stressors, cultural illness representations, attachment patterns and maternal environment. Studies in non-human primates also emphasize the complexity of the interaction of environmental factors with underlying biological vulnerability. Continued research on the pathophysiology of anxiety disorders has the potential to lead not only to new therapies but also to transform our nosology. Given the increasing sophistication and complexity of each area of study, one challenge for the future will be to maintain collaboration between researchers and clinicians with different types of expertise, so that advances in one area can spur advances in another.