Two young adults (aged 19 and 23 yrs) with initial average digit- and word-span memory were trained to memorize and reproduce strings of 80-90 digits presented at 10- to 1-sec rates. The instruction and training program, based on W. G. Chase and K. A. Ericsson's (1981) theory of skilled memory, focused on 3 components: acquisition of a mnemonic system (i.e., recoding digits into historical dates or concrete nouns), use of a long-term memory retrieval structure (i.e., instruction in the Method of Loci), and improvement in processing speed. After 86 sessions, 1 S recalled 90 random digits presented at a 1-sec rate. The digits were, however, constrained to be compatible with the S's historical knowledge. The 2nd S recalled 80 random digits presented at a 5-sec rate after 70 sessions. Speed of encoding and retrieval processing was the only component that required extensive practice for skilled digit-memory acquisition. (PsycINFO Database Record (c) 2007 APA, all rights reserved)