International Society of Arboriculture

The ISA serves the tree care industry as a paid membership association and a credentialing organization that promotes the professional practice of arboriculture.

[2] ISA focuses on providing research, technology, and education opportunities for tree care professionals to develop their arboricultural expertise.

[3][4] Worldwide, ISA has 22,000 members and 31,000 ISA-certified tree care professionals with 59 chapters, associate organizations, and professional affiliates throughout North America, Asia, Oceania, Europe, and South America.

[5] ISA offers the following credentials: The Certified Arborist credential identifies professional arborists who have a minimum of three years' full-time experience working in the professional tree care industry and who have passed an examination covering facets of arboriculture.

The certification began as a result of the need to distinguish the top few arborists and allow others to identify those with superior credentials.

James Kinder, an ISA Certified Municipal Arborist, examining a Japanese hemlock at Hoyt Arboretum
A Hinoki cypress receiving some corrective pruning by a certified arborist in Oregon