This presentation outlines the aims and results of the LSAC / AEDI validation study, which seeks to use comparable data from 'Growing Up in Australia: the Longitudinal Study of Australian Children' (LSAC) to assess the Australian Early Development Instrument's (AEDI) construct and concurrent validity as an indicator of early child development at ages 4-5 years, and its behavioural and social outcomes at ages 6-7 years. Section 1 introduces the development and domains of the AEDI, and its use in communities across Australia (maps included). Section 2 compares AEDI and LSAC domains and its predictive performance. The conclusions of section 3 support the soundness of AEDI.