Magnetoencephalography (MEG) is an exceptionally useful tool to study child development. It measures brain waves: fluctuations in the magnetic field around the head caused by changes in the local field potential of neuronal populations that fire in synchrony. MEG has a high-temporal resolution, and a reasonable degree of spatial precision. It offers insights into how the brain responds to events, how brain rhythms affect perception and performance, and how different areas talk to each other. In addition to its scientific benefits, MEG is safe, silent, and requires relatively little setup time. In this chapter, the authors outline the origins of the MEG signal, provide practical tips specific to testing children, and describe a wide variety of analysis methods.