Spectropolarimetry embraces the most complete and detailed measurement and analysis of light, as well as its interaction with matter. This book provides an introductory overview of the subject because it is playing an increasingly important role in modern solar observations. Chapters include a comprehensive description of the polarization state of polychromatic light and its measurement; an overview of astronomical polarimetry; and the formation of spectral lines in the presence of a magnetic field. The text is a valuable reference for graduates and researchers in astrophysics, solar physics and optics.