Creating lifelike, autonomous, and interactive virtual behaviors is important in generating character animation, such as animal crowds, pedestrians, battle scenes, etc. Unfortunately, such task has long been limited to skilled users, since the authoring tools, including script languages and other commercial programs, mostly require lengthy prelearning process or are difficult to use. A novel approach, gesture-based behavior authoring, is proposed to open the interesting experience of creating autonomous animated characters to novice users. The technique enables users to efficiently prototype behaviors of a character, with the potential for further refinements. With several testees, our gesture-based authoring manner has been verified to be beneficial to the addressed problem, and, grounded on the HCI (human-computer interaction) literature, the authoring process is direct, easy, and enjoyable.