This book, which is published in the early phase of ESA s Infrared Space Observatory mission, provides a comprehensive summary of the knowledge in this field of astronomy. In a series of invited review lectures and numerous contributed papers the role of dust in the formation of stars is described and discussed. Dust is ubiquitous in star-forming regions, protostars, young stellar objects and stars in various pre-main-sequence stages up to perfectly normal main-sequence stars. Consequently the authors address the topic from rather different viewpoints. Observers describe and analyze signatures of dust in the entire electromagnetic spectrum from the radio to the ultra-violet. Successfull modelling of these signatures with radiative transfer codes is demonstrated for a great variety of sources. Astrophysical laboratory researchers report on studies of synthetic prototype samples of interstellar dust. Other topics covered in this book are dust processing, dust agglomeration, dust coupling to the magnetic field or dust electric charging. Moreover, the reader will learn about dust chemical composition, gas-phase chemistry and photo-chemistry. From a mostly theoretical viewpoint the role of dust as a catalytic agent for star formation is described in great detail.