Public health guidelines contain recommendations for public health policy on what should be done in specific situations to achieve the best (health) outcomes, individually and collectively. Development of such guidelines is a complex process involving multiple perspectives and considerations. In this talk, I will describe the procedures of public health guideline development making the case for the adoption of a complexity perspective and the use of multiple types and sources of evidence beyond evidence of effectiveness. I will draw on the ongoing methodological work in developing evidence to decision frameworks and approaches to facilitate the application of such a perspective in guideline development, as well as case illustrations from the published and ongoing World Health Organization (WHO) guidelines.