In 1990 Gathercole and Baddeley proposed a strong hypothesis that has generated a wealth of research in the field of language development and disorder. The hypothesis was that phonological memory, as indexed by nonword repetition, is causally related to vocabulary development. Support for the hypothesis came from an impressive range of longitudinal, correlational, and laboratory training studies, and from studies of specific language impairment (SLI). However, more recently, Gathercole, Tiffany, Briscoe, Thorn, and The ALSPAC Team (2005), directly tested the causal hypothesis by following a cohort of children from age 5 to 8 years. Contrary to prediction, children with poor nonword repetition abilities at age 5 had normal vocabulary at the age of 8.