Using data from a longitudinal comparative study of children at risk of dyslexia (Snowling, Gallagher & Frith, 2003), this paper reports some replication of work by Gibbs (2004). It was found that the development of phonological awareness might, for children between the ages of 6 and 8 years of age and not considered to be at risk of dyslexia, be facilitated by an interaction of memory span and lexical knowledge. This effect was not, however, found for children of the same age who were considered to be at risk of dyslexia. For these children an interaction, with contrasting implications, was found between the ages of 3 years 9 months and 6 years. Some theoretical and practical implications of these findings are outlined.