A well-known phenomenon in natural interaction is that speakers adapt their linguistic and nonverbal behaviors. Research on gestural alignment is, however, still in its early stages based on evidence from experimental settings. This paper provides a first systematic study of gesture form convergence based on a large sample of naturalistic dialogue data. We found evidence for gestural alignment, but not all form features of co-speech gestures are subject to this effect. In a detailed analysis of those sensitive features we further address questions of how gestural alignment depends on the temporal distance between gestures, and whether intra-speaker or inter-speaker influences on gesture form are stronger.