A new family HEMIPHACIDIACEAE (earlier provisionally named Keithiaceae) is critically compared with the Phacidiaceae, Sticitidaceae and Dermateaceae, and embraces Didymascella (=Keithia), Rhabdocline, Fabrella, HEMIPHACIDIUM, GREMMENIA, and the doubtful genus Naemacyclus in the tribe HEMIPHACIDIEAE, as well as the genus Sarcotrochila (including Stegopezizella) and the doubtful genus Lophophacidium (= Neonaumovia) in the tribe SARCOTROCHILEAE. The I reaction of the ascus pore, blue in Melzer''s reagent in the Sarcotrochileae, non-reactive in the Hemiphacidieae, is stressed. The problem of juvenility and maturity in ascospores with particular reference to pigmentation and septation is discussed in members of this family and in the sclerotiniaceous genus Lambertella. Keys are provided to the major families of Ascomycetes associated with needle-casts and needle-blights and to the tribes, genera and presently known spp. of the new family. Certain excluded genera and spp. are discussed in detail. Stegopeziza is transferred to the Hyaloscyphaceae. A new term, discothecium, is coined for the apothecium-like ascostroma characteristic of certain bitunicate Ascomycetes. New combinations are H. planum (= Phacidium planum Davis), H. convexum (= Phacidium convexum Dearness), G. gigaspora (= Phragmonaevia gigaspora Gremmen), Sarcotrochila balsameae (= Phacidium balsameae Davis), S. piniperda (= Naevia piniperda Rehm). One new ssp., Fabrella tsugae ssp. grandispora Ziller, on Tsuga heterophylla, is characterized.