Technical Abstract: Edhazardia aedis, a pathogen of Aedes aegypti, has a complex life cycle involving both horizontal and vertical transmission affecting two successive generations of the host. Usually, one sporulation sequence occurs in the adult female (infected orally as a larva) and results in the formation of binucleate spores. These spores are involved in vertical transmission of E. aedis to the subsequent generation via infected eggs. In infected progeny, larval death results in the release of uninucleate spores that are responsible for horizontal transmission when ingested by larvae. This developmental sequence leads to the formation of binucleate spores in the adult to complete the cycle. Optimism regarding the role of E. aedis as part of a program to control Ae. aegypti focuses on a number of desirable traits. Both the vertical and horizontal components of the life cycle of E. aedis are highly efficient providing the means for the parasite to become established, persist and spread in populations of Ae. aegypti. Edhazardia aedis has a profound effect on the reproductive capacity of these infected adults with a 98% reduction in overall fitness by reducing survival, fecundity and the percent of eggs that hatch. Good persistence is expected in release sites due to life cycle flexibility with dissemination to other mosquito-inhabiting sites by means of vertical transmission. Survival during dry periods occurs within the mosquito eggs where the parasite can survive for the life of the egg. The possibilities and challenges of utilizing E. aedis as a classical biocontrol agent will be discussed.