This report was written from the notes used by Dr. York in delivering his three lectures on considerations pertinent to the problem of utilizing controlled thermonuclear reactions for the production of power. The first lecture discussed fundamental properties of the DD and DT reactions and the reacting substances. The second lecture described the stellarator, a proposed machine for the controlled production of power from the above reactions. The third lecture described the pinch effect and considered its possible application to the thermonuclear power problem.