Embodied conversational agents are required to be able to

express themselves convincingly and autonomously. Based

on an empirial study on spatial descriptions of landmarks

in direction-giving, we present a model that allows virtual

agents to automatically generate, i.e., select the content and derive the form of coordinated language and iconic gestures. Our model simulates the interplay between these two modes of expressiveness on two levels. First, two kinds of knowledge representation (propositional and imagistic) are utilized to capture the modality-specific contents and processes of content planning. Second, specific planners are integrated to carry out the formulation of concrete verbal and gestural behavior. A probabilistic approach to gesture formulation is presented that incorporates multiple contextual factors as

well as idiosyncratic patterns in the mapping of visuo-spatial referent properties onto gesture morphology. Results from a prototype implementation are described.