This research project provided microbial characterization support to the Waste Management Systems (WMS) element of NASA's Life Support and Habitation Systems (LSHS) program. Conventional microbiological methods were used to detect and enumerate microorganisms in space-generated solid wastes, i.e., STS Volume F Compartment trash returned from orbit and missions to ISS. Crew generated STS trash was characterized for three shuttle missions: STS 133, STS 134, and STS 135. The waste was catalogued into logical categories, weighed, and the water content determined. Results for FY11 STS missions showed more variability than for the FYlO study of STS 129-132 and indicated some waste was probably not included in what was returned to KSC on the STS. Microbial characterization of wastes from each mission and each category determined the presence of high numbers of microbes in food waste and food packaging, in drink pouches, and in personal hygiene wastes. A number of bacteria and fungi were identified, including known pathogens and some likely opportunistic pathogens that could cause problems if these wastes were exposed to an immune compromised crew.