Technical Abstract: Chalkbrood is an invasive mycosis in honey bees (Apis mellifera L.) produced by Ascosphaera apis (Maassen ex Claussen) Olive and Spiltoir (Spiltoir, 1955) that exclusively affects bee brood. Although fatal to individual larvae, the disease does not usually destroy an entire bee colony. However, it can cause significant losses in terms of both bee numbers and colony productivity (Bailey, 1963; Wood, 1998), with reductions in honey production of 5 to 37% reported (Heath 1982a; Yacobson et al. 1991, Zaghloul et al. 2005). Chalkbrood is now found in honey bee colonies around the world, and there are some indications that the incidence of chalkbrood has increased in recent years (Heath, 1985; Kluser and Peduzzi, 2007). Aizen et al. (2009) have shown that human activities related to increased food demand have direct and indirect effects that could be at least in part responsible for this trend. In this review, we consolidated historic knowledge and recent scientific findings focusing on pathogen biology, disease pathogenesis, and control methods. Significantly, since previous reviews were published, the entire genome of A. apis has been sequenced - the first fungal entomopathogen genome to be sequenced (Qin et al., 2006). Therefore, recent findings will include genomic and molecular studies not covered by previous reviews, including identification of the mating type locus (Aronstein et al., 2007). In the future, genomic research is expected to yield a better understanding of mechanisms controlling reproduction and pathogenesis in A. apis, and these discoveries will hopefully translate into increasingly effective disease control strategies.