From a review of national and international methodologies for describing and measuring ICT integration, there was found to be a lack of substantial history and development with most studies undertaken since 1998. Moreover, most studies have focussed on input indicators such as student to computer ratios, expenditure on ICTs, and the training and professional development of teachers. Within a context of emerging large scale investigations (e.g. SITES, EnGauge and Becta) there have been accompanying pressures for the development of methodologies for measuring ICT use and student outcomes at classroom, school and system levels. This paper provides a summary of the methodology used to evaluate Education Queensland's ICT Curriculum Integration Performance Measurement Instrument. The evaluation involved three major data sources - statistical analysis of the data collected from 929 Education Queensland teachers in 38 schools who used the Instrument in 2003; a peer review process; and school-based teacher interviews involving 42 teachers from 6 selected Queensland schools. The resulting recommendations derived from the evaluation informed the refinement of the Instrument which is now called Learning with ICTs: Measuring ICT Use in the Curriculum. This paper also summarises the recommendations and significant features of the Instrument.