Halcyon Optical Services has introduced T-Gauss beam-propagation software that provides Gaussian beam transformation through optical systems and that is suitable for use by optical fiber engineers, laser scientists and physics students. A single-lens transformation is based on five re- lated parameters: object size and position, image size and position, and the focal length of the lens. When the user enters three parameters, the software's "back computation" capability calculates the remaining two. The multiple-lens facility handles any combination of lenses and windows, and generic curves help the user visualize the behavior of Gaussian beams. A free 30-day demo CD is available upon request.