New Frontiers in Biomagnetism contains selected papers based on presentations at the 15th International Conference on Biomagnetism (Biomag 2006), held in Vancouver between the 20th and 26th of August, 2006. The conference brought together over 500 scientists and specialists from around the world to present the latest scientific and technological developments in the field of Biomagnetism - the measurement of magnetic signals produced by electric currents in the human body. The study of the minute magnetic fields resulting from heart and muscle contraction, signal conduction in the nervous system, or by the magnetization of biological tissue has grown steadily since the 5th World Conference on Biomagnetism that was held in Vancouver in August of 1984. Although the conference covered many facets of biomagnetism research, the focus for this year's conference was on new frontiers in biomagnetism - the development of new applications and areas of research. One emphasis was on the application of Magnetoencephalography (MEG) to the study of human development and its potential to help understand the physiological underpinnings of language and cognitive development in children, including neurodevelopmental disorders, such as Down Syndrome, autism and language impairment. There were also many exciting contributions on the latest techniques for the precise localization of brain activity using MEG, and related methods for the study of brain dynamics and distributed networks of neural activity. These novel approaches to the study of human brain function promise to provide new insights into the organization of neural systems underlying motor planning, perception, memory and cognition. Other areas of rapid development discussed in New Frontiers in Biomagnetism include the application of biomagnetic measures in the diagnosis and treatment of epilepsy, psychiatric disorders such as schizophrenia, and the use of MEG for presurgical functional mapping. Special sessions were also dedicated to the latest developments in Magnetocardiography (MCG) for the assessment of cardiovascular disease and associated disorders of the electrical activity of the heart. This year's conference also held a special symposium in honour of the late Sam Williamson, with presentations from his former colleagues and students that reviewed his life's work and contributions to the field of neuromagnetism. New Frontiers in Biomagnetism aims to provide a comprehensive overview of the latest developments in the field of Biomagnetism and its application to the study of human biological systems. The many new developments and breakthroughs presented at Biomag 2006 made a significant contribution to the advancement of the understanding of brain and cardiac function and provided new tools for clinical applications of this new knowledge.