For individuals who have complex communication needs and for the interventionists who work with them, the collection of empirically derived data that support the use of an intervention approach is critical. The purposes of this study were to continue building an empirically derived base of support for, and to compare the relative effectiveness of two communication intervention strategies (i.e., PECS and the use of VOCA) with preschool children who have complex communication needs. Specific research questions were (a) Which communication strategy, PECS or VOCA, results in a more rapid rate of acquisition of requesting skills for preschool children?, and (b) To what extent do communication behaviors utilizing PECS and VOCA generalize from a pull-out setting to the classroom setting? Results are discussed and clinical implications given. (Contains 6 figures and 1 table.)