Children with speech difficulties form the largest group of those referred to children?s speech and language therapy departments. Though some children grow out of their difficulties, others have persistent problems that can affect their educational progress and social development. Previous research into children?s speech impairments has been unable to agree on the percentage of the population who are affected by this. In addition, a number of factors such as intelligence and family factors have been found to be associated with speech impairment though there is no conclusive agreement on which factors are most important. Similarly, the degree to which educational and social development is affected is in dispute. Some speech impairments are associated with anatomical or neurological impairments such as cleft palate or cerebral palsy, but for a large number of children, there is no identifiable cause. Research has suggested many possibilities and it is also thought that different subgroups may exist. Some of the research on speech impairments is now outdated and uses definitions of speech impairment that are no longer accepted. With the more recent studies, there has been a tendency to use small samples of children, in some instances just one or two cases. There is therefore an urgent need for population-based research. The Avon Longitudinal Study of Parents and Children (ALSPAC) is a large scale study of children?s development which has collected information on children?s speech development at ages 2, 5 and 8. This provides a unique opportunity to investigate some of the questions surrounding speech impairment. The proposed study will identify the percentage of children aged 5 and 8 years who have speech impairments, what factors predict persistent problems and what factors are associated with a good prognosis . It will identify outcomes for children with speech impairments and investigate the existence of any subgroups. The researcher team have considerable expertise in the field of children?s speech impairment as well as being familiar with the data collected in the ALSPAC study. Findings from this study will support the early identification of children at risk of persisting speech impairments and help to identify interventions which may prevent long term negative outcomes. In addition, a clear understanding of the numbers affected by these difficulty together with information on the factors which are associated with it, will enable services to be planned more effectively and resources targeted where they are most needed.