Aerosol techniques provide a convenient method for generation of small particles of high purity and a wide range of chemical formulations. Here we will emphasis the method of aerosol spray pyrolysis wherein solutions of precursor salts are nebulized and then dried and pyrolyzed in a furnace reactor. This method can be used to create a wide variety of complex, multicomponent particles with typical sizes in the 50 nm to 500 nm range. Problems involving nondense morphology (often hollow and/or porous particles) and chemical phase segregation must be addressed, and schemes to defeat these problems are given. Examples from our work to create complex metal oxides (ferrites and garnets) will be used to show phase and morphology evolution during synthesis. The magnetic properties of these particles are similar to the bulk materials but with variations due to particle size and preparation scheme.