Field Studies in the Lasiosphaeriaceae and Helminthosphaeriaceae Sensu Lato represents some 10-15 years of part time field studies on wood inhabiting fungi belonging to the ascomycete families Lasiosphaeriaceae & Helminthosphaeriaceae sensu lato. The research was undertaken in New Zealand and to a lesser extent during visits to the United States. The principle reason for doing it was to provide tangible means of identifying the collected species and thereby to encourage further field work by all interested parties. Due to the increasing use of sequencing data in recent years, the introductory chapter deals with some of the current difficulties faced when trying to unite sequencing data with traditional morphological data. Keys to species are provided and each species, including 12 new ones, are fully described and illustrated. Photographs and coloured drawings comprise the greater part of the publication.