The properties of microwave/millimeter wave nonlinear magnetic excitations in bulk and thin film magnetic materials are to investigated experimentally. Two key manifestations of nonlinear dynamics in magnetic systems will be studied: (1) high-frequency spin wave solitons, and (2) nonlinear spin-wave-interaction- driven auto-oscillations and chaos. The primary tools for these studies will be Brillouin light scattering, utilizing/high contrast and high-resolution Fabry-Perot interferometry, and microwave/millimeter wave pulse techniques.