Abstract: A humidity control apparatus and methods for use with, e.g., an environmental test chamber. In one embodiment, the apparatus comprises a system having a test chamber, a water tank, motive source for a gaseous humidity carrier, and temperature controllers for the tank and chamber. The carrier gas (e.g., air) is diffused through the water tank, thereby saturating the gas to a prescribed humidity level. This saturated gas is then passed into the chamber, and the environment within the chamber (i.e., humidity and temperature) controlled by the controller(s) so as to maintain the desired humidity level. The apparatus disclosed has the primary advantage of reducing or even substantially eliminating condensation within the test chamber when humidity levels are increased.