There is growing recognition in Australia of the importance of early childhood to later health and wellbeing, with developments such as the National Agenda for Early Childhood and the National Public Health Action Plan for Children. To sustain a policy agenda for children and improve long-term outcomes, we need timely, comprehensive and accurate indicators and data on child health, development and wellbeing. Building this evidence requires a national monitoring and surveillance system that involves more than aggregating or linking existing data. Steps to building a national system are: to agree on key indicators of child health, development and wellbeing for regular reporting, to research a comprehensive set of indicators for each domain and ascertain data gaps, and to ensure development and coordination of data relevant to policy-making.