The display repertoires of three sibling species of Anolis lizards, were quantitatively analyzed and described. These species are distributed along Haiti's western coast with no major geographic barriers separating their populations. Anolis websteri is the northernmost species, Anolis caudalis is centrally located, and Anolis brevirostris is the southernmost species. Except for contrasting dewlap color at the species contact zones, they are identical in physical appearance. Behavioral mechanisms have been implicated in the reproductive isolation of the species. Because the head bob displays consistently incorporate the dewlap and are important in anoline communication, they may be the focal point of this isolation. This study documents a species-unique display repertoire for each of the siblings and thereby supports this hypothesis. Analysis of 736 head bob displays revealed that each species possesses one stereotyped Type A display and one to three stereotyped B displays (A. caudalis, one; A. brevirostris, two; A. websteri, three). Each species' A display resembled that of its siblings, however, discriminant analysis procedure clearly discriminated between the three species' A displays. This procedure also demonstrated differences between the Type B displays. The six kinds of Type B displays in the combined repertoires were considered derived from one B display pattern. An interpretation of the evolutionary sequence of these patterns is provided in a cladogram in which the A. caudalis display was considered the outgroup. The cladogram shows the three displays of A. websteri are the most apomorphic and the two displays of A. brevirostris the most plesiomorphic. / Master of Science