This paper presents a model for interactive animation (IAN) of structured objects in multimedia documents. The model naturally integrates usual multimedia elements (text, image, video, sound) with motion and graphical changes of geometric objects, but also with user and inter-object interaction. Animation is defined in a declarative and highly structured manner: a set of objects with their properties and composition relations and a scenario com-posed of a set of event-condition-action rules. Our pur-pose is to enable both easy authoring and database man-agement of animations. The paper aims at a sound defini-tion of the basic animation model, providing a clear se-mantics for time-dependent transformations and animated objects composition. The scenario model and the database issues are briefly described and illustrated by examples.