Kinematic dynamo action in an unbounded homogeneous, fluid conductor is studied from an exact, analytical viewpoint, by exploiting the mathematical tractibility of “helical symmetry,” uncovered by Lortz [1968a). The principal motivation is to elucidate how helical dynamos operate, to clarify their energetics, to extend Lortz's work where possible and to place helical dynamos within the more general context of dynamo theory.