This chapter treats several approaches for employing nanophotonics or near-nanophotonics concepts to create low-power switches. The partly interrelated issues of low-power dissipation and small device footprint are elucidated and figures of merit for switches formulated. Both optically and electronically controlled optical switches are treated and the crucial role of material development emphasized, illustrated by several examples, including both theoretical analysis of switch concepts and experimentally realized switches. Thus, electronically controlled switches based on hybrid, metamaterial, and nanoparticle plasmonics, electrooptic polymers as well as switches based on silicon and photonic crystals are discussed. The all-optical switches focus on third-order nonlinear effects and carrier-induced refractive index changes in III–V materials, as well as on emerging concepts of near-field-coupled quantum-dot switches. A brief comparison to electronic switches is done.