Planetary Stewardship is an ESA framework aimed at rapidly reducing human damage to the biosphere. To do this ecologists must collaborate with other natural and social scientists – as well as with practitioners--resource harvesters, land managers, decision makers, and other concerned citizens – to explore and implement solutions. Humankind’s past actions have already committed the planet to a substantially altered future. Yet some human stewardship practices have sustained their resources and environments through centuries, including windows of variable climate and episodes of catastrophe. The task ahead is to learn from them and find creative and scientifically defensible actions that minimize risks of further resource or ecosystem degradation, and maximize opportunities to sustain and restore natural ecosystems and the services they provide. Toward the same goal a group of natural scientist, social scientists, and scholars from the humanities inaugurated a Millennium Assessment of Human Behavior (MAHB). The MAHB (http://mahb.stanford.edu/) is starting a broad global discussion with each other and the general public to find ways that human behavior, toward other people and toward the planet that sustains all of us, can be rapidly modified. MAHB aims to expose society to the full range of population-environment-resource-ethics-power issues, and also to encourage cooperative research into ways to effect cultural change. The MAHB is in its early stages, but is already enhancing cooperation between ecologists and social scientists in ways that will be described. The ongoing Stewardship-MAHB collaboration will obviously not reach all its goals rapidly. Throughout, the participation of ecologists will be essential to assuring that environmental science perspectives are sound. The symposium will present views of a diverse group of scholars from outside of environmental science on these issues. Finally there will be a broad panel-audience interchange that will allow ecologists an opportunity to present their reactions.