This book reviews the present knowledge of collision-induced absorption of infrared radiation in the dense, common gases. Following a brief introduction and review of essential background information, such as dipole radiation, molecular collisions and interactions, numerous experimental results for the absorption spectra of dense gases are presented. Other chapters review the causes and properties of dipole moments induced by molecular interactions, the theory of collision-induced absorption in monatomic gas mixtures and in molecular gases and mixtures. The final chapter discusses related phenomena and the important applications in astrophysics. Throughout the book, the emphasis is on the absorption by binary molecular complexes, but the onset of many-body effects, such as the ternary contributions and the intercollisional process, are also considered. The volume is meant to be a practical guide and sourcebook for the researcher interested in the spectroscopy of dense, neutral fluids. This edition includes a new appendix reviewing recent work.