Characters of conidiophore and conidium development are used for the separation of some common temperate and a few tropical Hyphomycetes into eight Sections. The need for further studies on the precise method of conidium development is stressed because this promises to provide the most stable character for the classification of Fungi Imperfecti as a whole. Conidiophores and conidia of a large number of Hyphomycetes are figured to illustrate the various characters common to each Section.