The range of evidence at the archaeological site of Gesher Benot Ya’aqov (GBY) provides a window into the minds of 800,000-year-old Acheulian hominins. Detailed action sequences used in stone tool manufacture, and in the exploitation of animals (over 70 taxa) and plants (over 130 taxa) are reconstructed, suggesting hierarchically organized decision chains with multiple alternative pathways to completion. In terms of complexity and organization, these action sequences rival those of modern hunters and gatherers and are typical of a cognitive strategy known in psychology as expert cognition, or expertise. In the modern world expert cognition drives many of our most esteemed activities, including chess, sport, musical performance, and medical diagnosis. Cognitive models of expertise emphasize the role of retrieval structures, which are chunks of information activated in working memory and linked by association to much larger chunks of information held in long-term memory. The evidence from GBY documents the importance of long-term memory, prospective memory, and cognitive control, and suggests that expert cognition has been an important strategy in hominin cognition for at least 800,000 years.