This paper reports on the longitudinal results of a large project involving 242 seven-year-old children attending language units in England. Following our work outlining 6 subgroups of children with language impairment (Conti-Ramsden, Crutchley, & Botting, 1997), we examine the stability of the 6 subgroups of children with specific language impairment already identified, using data collected from the same children at age 8 years. The findings suggest there is considerable stability in the patterns of difficulties delineated by the classification system involving 6 subgroups. Poorer stability was evident in the classification of the children across time with 45% of children moving across subgroups. The membership stability of the proposed classification system was very similar to that found when the children were classified into 3 subgroups following another well-known system (Rapin, 1996). The findings are discussed with particular reference to issues surrounding the classification of children with SLI.