Focusing on deixis in human computer interaction this paper presents interdisciplinary work on the use of co-verbal gesture . Empirical investigations, theoretical modeling, and computational simulations with an anthropomorphic agent are based upon comparable settings and common representations. Findings pertain to the coordination of verbal and gestural constituents in deictic utterances. We discovered high variability in the temporal synchronization of such constituents in task-oriented dialogue, and a theoretical treatment thereof is presented. With respect to simulation we exemplarily show how the influence of situational characteristics on the choice of verbal and nonverbal constituents can be accounted for. In particular, this depends on spatio-temporal relations between speaker and the objects they refer to in dialogue.