This report describes the findings from the first three years of the ACER longitudinal Literacy and Numeracy Study (LLANS). The longitudinal study was established in 1999 in a context in which there was significant national interest in improving achievement in literacy and numeracy for all Australian children, and a particular interest in the development of foundational skills in the early years of school. A nation wide sample of 100 schools was selected in proportion to the population of each state and territory and ten students were randomly selected from each of these schools. This provided a cohort for LLANS of 1000 children who commenced school in 1999. The longitudinal study continued beyond the first three years of school until 2005 when the students in the sample were in year 6.