Dynamo theory is the study of how large scale magnetic fields can arise in bodies such as the Earth, Sun, and stars. This text brings together researchers in such diverse subjects as geophysics, astronomy, and nuclear reactor technology and covers topics such as modeling of solar magnetic field generation, theoretical studies of the dynamics of the Earth's core, studies of the magnetic fields in galaxies, and papers on "fast dynamos," the study of magnetic field regeneration in fluid of very high electrical conductivity. This volume represents the most comprehensive and up-to-date record of research into the theory of dynamos and will interest students and professors of astrophysics, applied mathematics, and planetary science.