The International Society of Arboriculture (ISA) Certified Arborist is a professional designation granted to individuals who have demonstrated a high level of knowledge and expertise in the field of arboriculture. This certification is recognized globally and is often a requirement for advanced roles within the tree care industry.

Arborists are professionals trained in the art and science of planting, caring for, and maintaining individual trees. They are knowledgeable about the needs of trees and are trained and equipped to provide proper care. The ISA Certified Arborist credential identifies professionals who have a minimum of three years of full-time experience working in the professional tree care industry and who have passed an extensive examination covering all facets of arboriculture.

History of ISA and the Certification

The International Society of Arboriculture was founded in 1924 when forty individuals, each engaged in a phase of tree work or research, were called together by the Connecticut Tree Protection Examining Board to discuss shade tree problems and their possible solutions. It was during this meeting that the group organized the ISA, and the concept of arboriculture began to gain momentum.

Since then, the ISA has been a dynamic medium through which arborists around the world share their experience and knowledge for the benefit of society. The ISA, aligned on many fronts with other green organizations, is working hard to foster a better understanding of trees and tree care through research and the education of professionals as well as the public.

The ISA Certified Arborist program was established in the 1980s as a way for tree care professionals to demonstrate their commitment to the profession and the industry. The program is built on the premise that certification is a voluntary process by which individuals can document their base of knowledge. It operates without mandate of law and is an internal, self-regulating device. By becoming an ISA Certified Arborist, professionals show their dedication to the profession, the industry, and the environment.

Requirements for Certification

To earn an ISA Certified Arborist credential, you must be trained and knowledgeable in all aspects of arboriculture. ISA Certified Arborist have met 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 work experience must be directly involved with the care and maintenance of trees. This can include tree maintenance, pruning, cabling and bracing, problem diagnosis, tree removal, and tree worker aerial lift. Other acceptable areas of service can include arboricultural consulting, arboricultural education, landscape architecture with an emphasis on trees, and research on tree care practices.

Once the eligibility requirements are met, the individual must then pass the ISA Certified Arborist exam. The exam is comprehensive, covering every aspect of tree care and the individuals must have an acceptable level of knowledge in all areas of arboriculture.

Benefits of Hiring an ISA Certified Arborist

ISA Certified Arborists are individuals who have achieved a level of knowledge in the art and science of tree care through experience and by passing a comprehensive examination developed by some of the nation’s leading experts on tree care. They are also required to continue their education in order to maintain their certification, ensuring their knowledge is updated on the latest arboriculture techniques.

ISA Certified Arborists are also required to adhere to a Code of Ethics that strengthens the credibility and reliability of the workforce. This Code of Ethics was established to enhance the internal and public trust in the arboriculture profession. It is a set of principles and guidelines that all ISA Certified Arborists must follow in the execution of their professional duties.

Therefore, when hiring an arborist, considering one that is an ISA Certified Arborist can ensure that the individual has a minimum level of knowledge and expertise recognized by the industry, and that they are committed to continuing education and adherence to a code of ethics.

ISA Certification Types

While the Certified Arborist certification provides a measurable assessment of an individual’s knowledge and competence required to provide proper tree care, ISA offers several other certification types that recognize professionals with a greater depth of knowledge in specific areas of arboriculture.

The ISA Certified Arborist Utility Specialist, for example, is an individual who has the knowledge and skills needed to provide for or supervise the management of trees and vegetation for the purpose of maintaining clearances for utility lines. They must have the Certified Arborist certification as a prerequisite and meet additional experience requirements.

The ISA Certified Arborist Municipal Specialist is another certification type. This certification recognizes individuals who have the knowledge and skills needed to manage urban trees. Like the Utility Specialist, this certification also requires the Certified Arborist certification as a prerequisite and additional experience requirements.

These are just a few examples of the types of certifications offered by ISA. Each certification has its own set of prerequisites and requires passing a separate examination.

Continuing Education and Recertification

Once an individual has become an ISA Certified Arborist, it is not a lifetime credential. The certification is valid for three years. To maintain the certification, individuals must complete a recertification process, which includes obtaining continuing education units (CEUs) and adhering to the ISA Code of Ethics.

Continuing education is an important part of the ISA certification program. It ensures that certified individuals stay updated on the latest best practices in arboriculture. ISA Certified Arborists are required to earn a minimum of 30 CEUs during the three-year certification period. They can earn CEUs through various activities that contribute to professional development and involve the science and practice of arboriculture.

If the ISA Certified Arborist does not meet the recertification requirements within the three-year period, the certification will expire. If the certification expires, the individual will need to retake and pass the exam to regain their certified status.


The ISA Certified Arborist credential is a mark of professional distinction and is highly respected in the arboriculture industry. It represents an individual’s dedication to the profession, the industry, and the environment. By becoming an ISA Certified Arborist, professionals not only validate their competence and skill, but they also become part of an organization that is striving to make the world a better place through the proper care of trees.

Whether you are a tree care professional seeking to advance your career, or a consumer looking for qualified tree care services, the ISA Certified Arborist credential serves as a measure of assurance and quality. It signifies that the individual has met stringent requirements, passed a comprehensive exam, and is committed to continuing education and ethical conduct.