Specific Language Impairments (SLI) in childhood affect around 7% of the population, and provide a test case for developmental theories. The concept of SLI entails modularity, presenting a major challenge to neuroconstructivist approaches to development. By examining the extent to which SLI inhibits cognitive development in non-linguistic domains we can extend the evidence base for competing theoretical accounts. Recent work (e.g. Donlan et al.2007) showed that SLI exposes independence in development between language-dependent procedural skills (rote-counting) and higher-level conceptual understanding (application of arithmetic principles). This has practical as well as theoretical implications, motivating specific educational interventions. It also sets an agenda for further work exploring neural substrates and factors affecting their variability Work in progress in collaboration with Professor Cathy Price and Dr Michael Thomas explores long term developmental trajectories in SLI. Behavioural analyis of single cases suggest divergent long-term developmental profiles of functional language and phonological sysgtems which may be identifiable through fMRI. Donlan, C., Cowan, R., Newton E. Lloyd, D. (2007) The role of language in mathematical development: evidence from children with specific language impairment. Cognition, 103, 23-33.