- Pacific Tree Climbing Institute
- Registered outfitter/guide service offers customized trips and instructional programs designed to meet the diverse needs of most people regardless of age, experience or physical ability. Includes details of expeditions and education programs, news and FAQs. Located in Eugene, Oregon, United States.
- Tree Climbing Colorado
- Provides general information, pictures, FAQs, a calendar of events and a membership form. Located in Arvada, Colorado, United States.