Jeff Marion helped pioneer and develop the recreation ecology field of study, conducting research in parks and wilderness for several decades sponsored by the National Park Service and U.S. Forest Service. Many of these studies have both informed and evaluated the efficacy of various Leave No Trace low impact outdoor practices. Leave No Trace practices are “science based” to the extent they can be. For example, the core practices to concentrate use on existing trails and campsites in popular areas, while dispersing activities to prevent impacts in pristine areas is directly derived from numerous published studies. Other well-researched topics include guidance related to durable surfaces, methods of waste disposal, low impact campfire and wildlife protection practices, and social science studies focused on minimizing crowding and conflicts. In the 1990’s Jeff became a founding member of the Leave No Trace Board of Directors and Chaired the Education Review Committee charged with fully developing the Leave No Trace Principles and low impact practices, educational materials, and courses. He later worked within the Boy Scouts of America to incorporate these practices into their books, educational materials, and courses. In 2014 he authored the official “Leave No Trace in the Outdoors” book and will be revising it in 2024. Other areas of his recreation ecology research have focused on the development and management of more sustainable trails and campsites and minimizing the impacts of informal (visitor-created) trails and rock climbing. His publications can be most easily found and accessed at ResearchGate.