Protocol guide for the N. crassa yeast artificial chromosome library. Includes: Chromosome Walking; Hybridization screening of the YAC library; YAC restriction mapping and contig building; Preparation of chromosomal DNA plugs of YAC clones; Partial restriction enzyme digestion of YAC DNA plugs; Using CHEF gel analysis to resolve YAC clones; Southern Hybridization; Isolation of terminal restriction fragments from cloned DNA inserts in YAC clones; etc.