For microwave and millimeter-wave applications, there is increasing interest in using films rather than bulk ferrites. In some cases, such as magnetostatic wave devices, films provide definite performance advantages. In other cases, films may provide lower cost, smaller size, and enhanced compatibility with planar circuit designs such as monolithic microwave integrated circuits (MMIC). The author reviews some of the progress that has been made in development of single-crystal and polycrystalline ferrite films. He describes some of the ideas that are currently being considered for making these ferrites compatible with MMICs. The materials considered include garnets, spinels, and hexagonal ferrites. >