The timing of Health Impact Assessment has been widely discussed in relation to projects and the importance of early involvement is emphasized (WHO European Centre for Health Policy, 1999). However, since most policy making is incremental or cyclical, there is no obvious point for Health Impact Assessment to begin and no obvious point for the assessment report to be considered. The Health Impact Assessment process needs to be integral with the policy-making process. Like the policy it seeks to influence, Health Impact Assessment needs to be incremental, concerned with the relative advantages and disadvantages of minor policy adjustments rather than with fundamental changes, which are not deemed to be politically possible. Putters describes a system in the Netherlands where the Health Impact Assessment and the policy process are closely integrated (Putters, 1997). He notes how Health Impact Assessment, simply by increasing awareness of health, can change the policy-making process. An ideal state might be for the policy proponent to own the Health Impact Assessment and, except in cases of unusual complexity, perform it themselves. This contrasts with the current situation in Environmental Impact Assessment where the project proponent and the regulatory authority are distinct and sometimes adversarial. If those making Health Impact Assessments are to contribute to the policy-making process they must understand the policy maker's values. Assessments must conform to the policy- making timetable, furnish information in a form that is policy relevant (Milio, 1988) and fit the administrative structures of the policy makers.