The Interstellar Medium in Galaxies is a collection of reviews based on research into the interstellar medium (ISM) in the Milky Way and other galaxies. The book is appropriate both as an auxiliary text for graduate courses and as a basis reference for professional scientists. The articles cover current observations and theories on the components of the ISM, and they extend our knowledge of the Milky Way to the different and exotic conditions in other galaxies. For example, the effects of supernovae, galactic fountains, cooling flows, interactions and collisions, active nuclei, magnetic fields, starbursts, and mass loss by evolved stars are all discussed in this volume. The text also includes short articles on the techniques of mass determination for the gaseous and dusty components of the ISM. These articles are based on invited talks given at the Second Wyoming Conference on the ISM, held during July 1989, in the Grand Teton National Park, Wyoming, U.S.A.