This document collates the principles for a state-of-the-art public participation practice. It is primarily designed for reference and use by those involved in public participation in IA. It is built on the experience in PP of many IAIA members, and has been written for IAIA members from different backgrounds and IA domains to improve ethics and quality in their practice. Accordingly, the principles presented here are broad, generic, and non-prescriptive. They emphasize PP as a pillar of IA, and are intended to be applicable at all levels and types of planned interventions (including at the strategic level), and with respect to the constraints of time, information and resources.Public participation, as well as IA generally, is expanding in use all around the world. This evolving context enables more and more IA practitioners from the humanities, medicine and social sciences, and applied and natural sciences to get involved or even to coordi-nate public participation. IAIA hopes that these principles will be used for improving the practice of PP in IA, as well as to stimulate discussion between stakeholders that will result in better projects, better development, collaborative governance and ultimately a more sustainable world.