National frontiers with ecosystems experiencing rapid changes pose difficult challenges for scientific contributions to democratic processes for environmental governance. We describe an innovative outreach model, the ‘Knowledge Exchange Train', which combines educational outreach with capacity-building mechanisms to broaden public participation in planning for sustainable development. This involved an international team of scientists and practitioners from conservation and development organisations who travelled across a tri-national frontier area of the south-western Amazon to share recent findings with local leaders and stakeholder constituencies of several municipalities. The Knowledge Exchange Train quickly increased public awareness in many places and provided a means of broadening participation in planning and governance. This model supports planning for sustainable development and can be adapted to other geographic contexts and topics.