The balance beam is a rectangular artistic gymnastics apparatus and an event performed using the apparatus. The apparatus and the event are sometimes simply called "beam". The English abbreviation for the event in gymnastics scoring is BB. The balance beam is performed competitively only by female gymnasts.

The beam is a small, thin beam that is typically raised from the floor on a leg or stand at both ends. It is usually covered with leather-like material and is only four inches wide.

Balance beams used in international gymnastics competitions must conform to the guidelines and specifications set forth by the International Gymnastics Federation Apparatus Norms brochure. Several companies manufacture and sell beams, including AAI (USA), Janssen-Fritsen (Europe) and Acromat (Australia). Most gymnastics schools purchase and use balance beams that meet the FIG's standards, but some may also use beams with carpeted surfaces for practice situations. While learning new skills, gymnasts often work on floor beams with the same dimensions and surface of regulation apparatus but are set a very short distance from or on the ground. They may also work on medium beams, mini beams, road beams, or even lines on a mat.

Originally, the beam surface was plain polished wood. In earlier years, some gymnasts competed on a beam made of basketball-like material. However, this beam type was eventually banned due to its extreme slipperiness. Since the 1980s, beams have been covered in leather or suede. In addition, they are now also sprung to accommodate the stress of high-difficulty tumbling, turns, and poses.

The Fédération Internationale de Gymnastique (FIG) publishes the apparatus's measurements in the Apparatus Norms brochure.

A beam routine must consist of:

The gymnast may mount the beam using a springboard or from the mat; however, the mount must come from the Code of Points. The routines can last up to 90 seconds.

For detailed information on score tabulation, please see the Code of Points article.