The effects of spatial density as a setting event on the social interaction of preschool children were examined in this review. A specific interest was the potential application of this setting event to children with special needs in inclusive settings. Twelve studies were examined revealing a range of methodological and technical difficulties in the extant research. Several studies reported significant effects, but results were inconsistent and very limited research examining students with special needs is available. Several suggestions for future research are offered including conduct of studies in typical preschool settings with representative group sizes, study of children with special needs, and use of research designs that allow idiosyncratic responses to interventions to be considered. Despite considerable recent interest and research on setting events, the body of research on spatial density is dated and methodologically problematic. It is suggested that renewed interest in this class of setting events might be appropriate.