Wing clapping is recorded for 14 species of Zygoptera and is illustrated and described for 8 of these, all Nearctic species. It is hypothesized that the inconspicuous clappings observed in d<5 of Coenagrionidae and Lestidae serve as generalized territorial declarations to competitors, but that the more conspicuous clappings in both sexes of Calopteryx serve an additional, more specialized function, that of communication between members of a pair declaring their presence to each other.