In this paper the major technological requirements for fusion power, as implied by current conceptual designs of fusion power plants, are elucidated and assessed. As the point of departure the four fusion reactor concepts that have been most thoroughly considered in these design studies are described; they are the mirror, the theta-pinch, the Tokamak, and the laser-pellet concepts. The required technology is discussed relative to three principal areas of concern: (a) the power balance, that is, the unique power handling requirements associated with the production of electrical power by fusion; (b) reactor design, focusing primarily on the requirements imposed by a tritium-based fuel cycle, thermal-hydraulic considerations, and magnet systems; and (c) materials considerations, including surface erosion, radiation effects, materials compatibility, and neutron-induced activation. The major conclusions of the paper are summarized in a final section where it is noted that research and development programs have been initiated to satisfy the technological requirements associated with the realization of commercial fusion power.