The book helps students mastering their theoretical physics courses by posing advanced and even challenging problems and providing their detailed solutions. It is divided into three areas: classical theory of fields, quantum mechanics and statistical physics. For each of these fields, the authors give a concise overview of the background and then provide problems (in total more than 450) at different levels of difficulty. The second, larger part of the book contains the detailed solutions to all problems, with discussions of their physical significance and possibilities for generalization and transfer to other fields.