From isa-arbor.com: "Through research, technology, and education, the International Society of Arboriculture (ISA) promotes the professional practice of arboriculture and fosters a greater worldwide awareness of the benefits of trees. This is our passion and serves as our mission statement."
To earn an ISA Certified Arborist® credential, a tree service professional must be trained and knowledgeable in all aspects of arboriculture. An ISA Certified Arborist® must meet all requirements to be eligible for the exam, which includes three or more years of full-time, eligible, practical work experience in arboriculture and/or a degree in the field of arboriculture, horticulture, landscape architecture, or forestry from a regionally accredited educational institute. This certification covers a large number of topics giving the candidates flexibility in the arboricultural profession. A code of ethics for ISA Certified Arborists® strengthens the credibility and reliability of the work force. This certification is accredited by the American National Standards Institute, meeting and exceeding ISO 17024.