With individual chapter titles that include 'Why bother with sex?' and 'Why sex is good' this was always going to be an interesting read, but truly this is a fascinating and timely book. Many of the 58 contributors together provide a comprehensive account of cutting edge developments relating to the nature and evolution of the mating-type locus, both in fungi capable of sexual reproduction and in those organisms with an apparent cryptic sexual cycle. The descriptions of the latter group are particularly fascinating, not least because elements of cryptic sexual cycles may influence virulence in pathogenic fungi. The authors also provide illuminating insights into the homothallism, heterothallism dichotomy and the remarkable multiallelic mating type systems of basidiomycetes. The book should prove invaluable to all students and practitioners of mycology and will hopefully help reinforce the importance of fungi both generally and as invaluable research tools and model organisms.