This chapter focuses on the electromechanical properties and applications of nanotubes. The dependence of the electronic properties on the structure implies that mechanical deformations can alter the band structure. This results in electromechanical effects such as piezoresistance and electrostatic actuation, which, together with the mechanical properties, may lead to nanotube-based mechanical sensors and actuators as well as more complex applications, such as oscillators or electromechanical switches. In nanotubes, piezoresistance may be useful for mechanical sensors as well as electromechanical switches. The electronic structure of a nanotube is that of a graphene sheet with an additional periodic boundary condition imposed by having been rolled into a cylinder, which quantizes the electron wavefunctions around the tube. Carbon nanotubes are not piezoelectric, but an effect has been demonstrated that should be useful for actuation. The unique mechanical and electromechanical properties of nanotubes may well find application in the emerging field of nanoelectromechanical systems.