After a brief review of quantum mechanics and a summary of conventional atomic theory, H. Friedrich discusses the structure of atomic spectra on the basis of quantum defect theory, which he deals with at a basic level. Special attention is given to highly excited states and to the influence of external fields, which can cause intricate and interesting effects in seemingly simple systems. Material on reaction theory is followed in the the final chapter by a treatment of special topics such as multiphoton absorption and chaos. The book conveys the level of advanced quantum mechanics required for practical applications in modern atomic physics. The presentation is straightforward, avoiding abstract formalism as far as possible.