Particulate emissions form a group of municipal sludge incinerators, three with multiple-hearth furnaces and one with a fluidized-bed furnace, were characterized. Objectives of the investigation were (1) to obtain specific elemental emission concentrations, and (2) to provide source inventories and source signatures, especially in terms of particle size, that would assist in the development and evaluation of source apportionment models. Three of the plants investigated in this study operated at or near autogenous burning conditions. Chemical element composition was determined for total and sized emission samples by x-ray fluorescence analysis. During this study considerable enrichment of several elements (S, V, Cu, Zn, Cd, Sn, and Pb) in the particulate emissions, relative to their content in the sludge, was observed. The largest average enrichment ratios were observed for cadmium (31), zinc (14), lead (9), and sulfur (8).