Methodological issues and future directions in the evaluation of early intervention programmes

Early intervention programmes have grown rapidly over the last 30 years. Despite numerous attempts to answer the apparently simple question of whether or not early intervention works, results to date have been equivocal. This paper looks at the reasons why this question has not been answered satisfactorily and suggests that this question may not, in fact, be possible to answer in a global sense. It is suggested that questions must be addressed to the evaluation of specific services rather than to the evaluation of early intervention as a whole.