In relation to the attempt to improve children's health or development, effective service designs require clarity of purpose as to the outcomes to be achieved, clear target group criteria, a strong logic model and well defined service components. Ideally, these requirements are summarized in a manual, alongside robust estimates of adequate demand for the service; and a clear statement of ethics.

The design process should involve clarity about what is being done on behalf of the child, how long the service will be provided, how intense the intervention will be and where it will take place.

Achieving the above criteria requires good epidemiological evidence, a strong grasp of the 'what works' literature and strong consumer consultation. Effective service designs will generally make the process of robust evaluation, for example using RCTs, more straightforward, especially if those responsible for delivering the service are involved in the design process.