The Early Numeracy Research Project is a three-year project aimed at identifying effective approaches to mathematics learning in the first three years of school. Assessments of numeracy were obtained by interviews with over five thousand children in March and November of 1999 and overlapping samples in March and November, 2000 and March 2001. Data were obtained for nine domains: Counting; Place value; addition/subtraction; Multiplication/division; Time; Length; Mass; Shapes; Visualisation and orientation. The data were transformed to approximate interval scales and the scaled data used to chart growth over a two-year period, and to demonstrate significantly greater growth in the trial schools (in which continuing professional development programs were provided) than in comparable schools (in which no such program was available).