The cultural significance of effigy pipes among southeastern groups during the Mississippian period (A.D. 1000-1600) has yet to be fully understood. Recent studies, however, have provided new archaeological contexts for framing explanations of their possible use and distribution among such groups. Apart from conjectures about their use as ceremonial objects, selection for effigy pipes in the Mississippian Southeast was directly related to fluctuating environmental and demographic conditions under which such objects were manufactured and distributed. These conditions provided the appropriate context for their emergence as costly signaling devices through which elite or special interest groups advertised fitness levels, typically expressed in displays of power and prestige. As signaling devices, effigy pipes attained their widest distribution in the Southeast during a time of environmental and demographic stability. Their decline was primarily the result of increasing climatic instability and widespread demographic upheaval--events that precipitated major disruptions in commercial and economic relations.