The commercial viability of high field tokamaks is critically dependent upon the development of high field, high energy superconducting magnets. In this paper, superconducting magnet development requirements are discussed in terms of superconducting materials, structural materials and magnet engineering. Superconducting and structural materials are evaluated for processing techniques, properties and applicability to large scale magnets. Both conventional low Tc and high Tc ceramic superconductors are considered. For structural materials, cryogenic steels as well as fiber reinforced composite materials are discussed. The application of advanced materials, in particular high Tc superconductors and fiber reinforced composites, poses unique engineering problems that must be addressed. These problems are exacerbated by the very large stored energy inherent to any large high field magnet. Potential solutions are analyzed and areas of uncertainty are identified. A 30 year development program leading to a 24 Tesla toroidal field coil for a commercial reactor is outlined.