Public health policy has the potential to produce great benefits for individuals and communities. There is growing demand that such efforts be rigorously evaluated to ensure that the expected benefits are, in fact, realised. Commonly, public health policy is evaluated by consumer acceptability, reach, or changes in knowledge and attitudes. Non-robust research designs are often used. But these approaches to evaluation do not answer three critical questions: Has a change in the desired outcome occurred? Was it a consequence of the policy and not some extraneous factor? Was the size of the change considered significant and cost-effective? We, a team of government and academic scholars working in research and evaluation, have examined some of the more common impediments to robust evaluation: political impediments, a lack of investment in evaluation capacity within bureaucracy, and the failure of academic researchers to understand the need for the evaluation of public health policy.