In astronomy, spectroscopy is the technique that often provides most insight into the physical make-up of an object. In his book, Prof. Jonathan Tennyson (University College London) sets out to connect observed spectral line features to the quantummechanical properties of atoms and molecules in the line-producing, radiating media. He covers the whole electromagnetic spectrum from [gamma]-rays to radio waves. As expert in molecular spectroscopy, Tennyson puts emphasis on molecules, and the systematics inline spectra. In his foreword, he rightly stresses the role of molecules for spectra in the infrared and mm-range which are covered by (at the time of publication) upcoming observing facilities like Herschel, JWST, and ALMA. He leaves out aspects relatedto the modeling of spectra and the description of the instrumentation necessary for their observation. The book emerged from a lecture course for third year students. It assumes some familiarity with quantum mechanics on the level of the hydrogen atom, but not beyond. It starts out from the hydrogen atom to develop the concepts necessary to understand the spectra of complex, multi-electron systems. It applies the developed concepts to spectra observed in various astronomical environments before continuing with molecular structure and the hierarchy of molecular line spectra. Each chapter is finished by a number of problems with worked-out solutions which is helpful for lecturers using the book in their courses, or for self-study- The third edition of Astronomical Spectroscopy examines the physics necessary to understand and interpret astronomical spectra. It offers a step-by-step guide to the atomic and molecular physics involved in providing astronomical spectra starting from the relatively simple hydrogen atom and working its way to the spectroscopy of small molecules. Based on UCL course material, this book uses actual astronomical spectra to illustrate the theoretical aspects of the book to give the reader a feel for such spectra as well as an awareness of what information can be retrieved from them. It also provides comprehensive exercises, with answers given, to aid understanding.