These are findings of theoretical interest from: (i) follow-up of a case study of a precocious reader; and (ii) normally developing readers who served as comparison groups. The precocious reader was first reported when 2-3 years of age (Cognition 74 (2000) 177). From 3 to 7 years of age her precocious reading development continued, her word reading accuracy increasing from the 8- to the 16-year-level, although her phonemic awareness skills remained underdeveloped relative to word reading. Nonword reading continued to develop rapidly. Her word reading, however, was more than phonological recoding. At 5 years of age, in comparison with reading-level matched normal 11-year-olds she exhibited strong effects of semantic characteristics of words and evidence of well-specified lexical orthographic representations. In common with normal comparison 11-year-olds, who had not received instruction in explicit phonics, her explicit letter-sound skills were underdeveloped but she possessed high speed and accuracy in nonword reading, a result most theories of the acquisition of reading fail to explain. Her responses to irregularly spelt nonwords indicated higher proficiency than the 11-year-olds in acquiring lexical orthographic representations not predictable from prior phonological recoding knowledge. It is considered that this proficiency contributes to an explanation of her precocious reading development. A mechanism of implicit lexicalized phonological recoding is involved which explains the dissociation of skills in both the precocious reader and normally developing readers.