What does learning in the outdoors involve? What are the benefits of outdoor experience--and learning? What approaches are effective? What are the benefits for teachers and schools? How can what happens in the "outdoor classroom" be best integrated with the "in-school" curriculum? The research summarised in this article explored these questions during 2004-2005. The study was funded by the Department for Education and Skills (DfES), the Countryside Agency, and Farming and Countryside in Education (FACE). A range of successful practice in out-of-school education exists already, and several initiatives, such as the "Growing Schools" programme, have provided examples of innovative, interesting and safe work. However, despite these successes, recent research has highlighted the need for stronger evidence of learning in the "outdoor classroom". In this article, the author and his co-researchers describe the outcomes of some major action research into learning in the "outdoor classroom".