The magnetic and related properties of lanthanide and actinide pnictides and chalcogenides have been compiled in subvolume 27B. While subvolumes 27B1–27B5 deal with lanthanide pnictides and chalcogenides of different type, the properties of actinide pnictides and chalcogenides are covered in subvolumes 27B6, 27B7 and 27B8. Subvolumes 27B7 and 27B8 (already published) deal with binary and ternary actinide pnictides and chalcogenides. The present subvolume 27B6a deals with actinide monopnictides together with isostructural monocompounds containing carbon as well as solid solutions with either cation or anion mixing. Data for actinide monochalcogenides will be presented in 27B6b. The literature has been reviewed up to the beginning of 2005. An index of substances at the end of this subvolume lists all compounds treated in this subvolume.