Summary: Macromedia Flash is a powerful and robust development tool. Because of its graphical, sound, and animation capabilities (and ubiquitous browser plug-in), major companies employ it in their website development (see www.nike.com or www.espn.com). These same features also make Flash a valuable environment for building multi-representational "movies" (a Flash term analogous to "applet" in Java) to illustrate mathematical ideas or simulate mathematical situations. The National Council of Teachers of Mathematicsâ€™ (NCTM, 2000) Principles and Standards for School Mathematics includes the Technology Principle as one of the six principles characterizing high-quality mathematics education. The Technology Principle states, "Technology is essential in teaching and learning mathematics; it influences the mathematics that is taught and enhances studentsâ€™ learning. This article contains brief descriptions of Flash movies that have been created to support mathematics learning and investigations through visualization, as envisioned in the Principles and Standards. (ERIC)