ABCD Gaussian Beam Propagation allows you to propagate Gaussian laser beams through standard optical elements (free space, dielectric, thin lens, and curved mirror) and monitor the beam properties. This is a straightforward multiplication of two-by-two matrices and its application on a user-defined complex radius. The program simply makes a point-and-click interface to an engine doing standard ABCD matrices and complex radius calculations. It provides a research tool for people working with lasers or it can be used (to some extent) as a teaching aid for an undergraduate course in optics. This version fixes bugs. For more information, click here.