In this article, the author presents findings of a project that focused on identifying elements in the learning environment that promote numeracy outcomes. The project--"Numeracy Research and Development Initiative"--was undertaken in eight schools across a range of settings within the three schooling systems in Queensland and was coordinated by Education Queensland. A research team of 10 primary mathematics educators formed from four Queensland universities collaborated with teachers and administrators in the project schools. The teacher-academic collaborations impacted positively on almost all the project teachers in terms of teacher mathematics knowledge, mathematics teaching knowledge, and classroom engagement (especially confidence). These factors, in turn, enhanced teachers' classroom practices and student numeracy outcomes. The collaborations also assisted teachers in planning connected units of work based on students' prior knowledge, in selecting and using appropriate resources, in organising and managing activity and discussion, and in reviewing their ideas about appropriate classroom enquiry. Teachers' beliefs about mathematics and its teaching, learning, and assessment were challenged and changed and this, in turn, was reflected in improved classroom practices that enhanced active learning, classroom enquiry, and students' numeracy outcomes.