"Public participation" is the involvement of people in a problem-solving or decision-making process that may affect or interest them.
Who? "The public" is actually many publics. Their interests will vary from being affected by the decision to having information or insights of value to having a role in acting on the decision. Take the time to see the project through their eyes.
What? The public may be asked for advice and assistance or they may be offered a voice in the actual decision, such as through a committee, because there is more than one way to make a decision. Various kinds of knowledge are generally treated as additive rather than competitive (that is, together they create a richer and common pool of understanding).
When? It should be done thoughtfully, intentionally, purposefully. Preparation and involvement should start early. The public involvement should carry through the course of the effort and be adapted as necessary along the way.
Where? Location costs (time and travel) for participants and for the agency should be thoughtfully considered. Generally speaking, it makes a positive impression on participants when an agency finds ways to make it easier for them to participate.
Why? The "why" is grounded in the belief and the practical reality that the public has a right to consultation and involvement; solutions and decisions will be the better and more durable because of it; and conflict can be better managed through it.
How? The form and degree of involvement can vary within a single project or program and among different projects or programs. Different techniques vary in associated time and expense costs.
Adapted From: Lessons from the Field: Real Strategies for Engaging and Informing the Public (8/2/2000).