Magnetic nanoparticles have been attracting much interest in the fields of advanced biological and medical applications such as drug delivery, magnetic resonance imaging, and array-based assaying as well as in the fields of separation science. This book presents current research in the study of the properties, synthesis and applications of magnetic nanoparticles. Topics include the synthesis of organic based magnetic nanoparticles-polymers and calixarene based magnetic nanoparticles; ferromagnetism in carbon and boron nitride nanostructures; and computer simulations, chemical syntheses and biomedical diagnosis using magnetic nanoparticles.