Reaerosolization or resuspension-that is, the reintroduction of previously airborne particles into the atmosphere-is a complex phenomenon. Microbial reaerosolization is particularly poorly understood because few studies have been done in this area, and many of the studies that have been performed are not in the peer-reviewed literature. The reaerosolization of Bacillus anthracis in outdoor environments is of particular concern because of its stability and potential for use as a biological weapon. This review pulls together data from more than 30 publications, spanning field and laboratory experiments, to summarize the current state of our understanding of Bacillus spp. reaerosolization in outdoor environments.