There is need for a holistic, comprehensive ECD monitoring system that covers the multiple facets (i.e. education, health, social protection and the social and economical context in which the child is born) of public and private ECD interventions in a country. Such a system is essential for ensuring that all children can reap the benefits of ECD. It serves as a means of support and oversight for monitoring the performance and planning of ECD policies and programmes in developing countries. The paper highlights the importance of comprehensive ECD monitoring for making evidence-based decisions, and discusses practical issues to take into consideration when developing such a system. One of the first steps is deciding what to monitor through the selection of a limited number of valid and measurable indicators that are aligned to policy and programme goals. In this respect the capacity of the government system should be thoroughly assessed, including 1) the identification and evaluation of existing administrative and other data sources; 2) a training needs analysis of the administrators who will operate the monitoring system to allow for strengthening their skills and prepare them for their future duties; and 3) consideration of the long-term costs of operating a monitoring system in relation to the (projected) available funds, in order to ensure the sustainability of the system.