Cartoon animation techniques have previously been used to enhance the illusion of direct manipulation in 2D graphical user interfaces. In particular, animation may be used to convey a feeling of substance to the objects being manipulated by the user. To lay a solid framework for this work, an extensive review of current applications of animation to user interfaces is presented. This chapter goes on to present an expansion of the 2D animation concepts to the domain of 3D interfaces for multimedia and virtual reality. This chapter focuses on the improvement of the legibility of users’ actions in 3D multimedia and virtual reality applications, and details animation effects to support this legibility. In particular, I present animation effects for 3D graphical object manipulation. These effects include a standard set of 3D direct manipulation operations which have been extended to include animated visual feedback to add substance, operation cues for the user and constraint visualisation. The visual feedback effects using 3D warping can substitute for haptic feedback, as in the case of the squashing of an object when pressed against a wall, or the stretching of an object to show frictional forces. Finally, a pinning effect is explored for multiple users’ manipulating a common object in a collaborative environment.