This paper presents experimental evidence that MEMS devices may be manipulated using beams of light. Light possesses momentum, and hence it imparts a force equal to 2W/c when perfectly reflected by a surface. Here W is the total power of the reflected light, and c is the speed of light. The radiation pressure of light can be quite significant to MEMS devices. This actuation method is demonstrated, both in air and in vacuum, by switching the state of a bi-stable MEMS device. The associated heat transfer model is also presented.