An arborist is a professional dedicated to the cultivation, management, and study of trees, shrubs, and other woody plants, focusing on the health and safety of trees in urban settings. These specialists provide expert care, including planting, pruning, diagnosis of pests and diseases, and risk assessment. Obtaining professional credentials showcases a foundational understanding of arboricultural science and industry best practices. This demonstration of knowledge establishes credibility with clients, protects the public through informed safety practices, and promotes quality within the tree care industry.
Certification Versus Licensing
The terms certification and licensing describe different types of professional recognition in the tree care field. Certification, most notably the Certified Arborist credential offered by the International Society of Arboriculture (ISA), is a voluntary process. It confirms an individual has met a high standard of knowledge and skill through examination and serves as the accepted benchmark for technical expertise across the industry.
Licensing, conversely, is typically a mandatory government requirement administered at the state or municipal level. This requirement focuses on the business or regulatory aspects of performing tree work, such as mandating general liability insurance, posting a performance bond, or registering a business entity. While ISA certification demonstrates knowledge, a government license grants the legal authority to operate a business or perform specific regulated tasks. This article focuses primarily on obtaining the ISA Certified Arborist credential before addressing state-level licensing requirements.
Meeting the Core Eligibility Requirements
Before a candidate can attempt the ISA Certified Arborist examination, they must satisfy specific prerequisites designed to ensure they possess a foundation of practical and theoretical knowledge. The ISA provides two distinct pathways for meeting these core eligibility standards, both of which require documented experience in the field of arboriculture.
The most direct route requires candidates to document a minimum of three years of full-time, practical work experience dedicated to the care of trees. This experience must involve the hands-on application of arboricultural practices, such as pruning, diagnosis, cabling, bracing, and general maintenance activities.
The second path allows for the substitution of formal education for a portion of the required work history. A candidate holding a two-year degree with coursework in a related field (e.g., horticulture, forestry, or landscape architecture) must supply documentation for two years of practical work experience. For those who have completed a four-year degree in one of these related disciplines, the experience requirement is reduced to just one year of full-time work. In both cases, the ISA requires documentation, such as official transcripts and letters from employers, to substantiate the claimed history.
Understanding the Application Process
The process for seeking certification begins once a candidate meets the minimum combination of experience and education. The first step involves submitting a formal application to the ISA through their online portal, detailing work history and educational qualifications. A non-refundable application fee is required, typically $40 for ISA members and $50 for non-members. The application must include supporting documentation, such as transcripts and employer references, for eligibility verification.
The ISA Credentialing Council reviews the documentation before granting permission to proceed to the examination. Once approved, the candidate receives authorization to schedule the exam and must pay the separate enrollment fee ($295 for members, $369 for non-members). This payment grants the candidate a window of time, usually 120 days, to schedule and sit for the examination at a designated testing center or a local chapter-sponsored event.
Preparing for and Passing the Certification Exam
The ISA Certified Arborist examination is a comprehensive written assessment consisting of 200 multiple-choice questions. Candidates are allotted three and a half hours to complete the examination. To successfully obtain the credential, a candidate must achieve a passing score of 76%.
The content is distributed across ten domains of arboriculture, reflecting the duties identified by the ISA. Safe Work Practices and Pruning represent the largest portions of the exam content.
Exam Domains
Safe Work Practices (15%)
Pruning (14%)
Tree Biology (11%)
Tree Risk (11%)
Trees and Construction (9%)
Installation and Establishment (9%)
Diagnosis and Treatment (9%)
Soil Management (7%)
Urban Forestry (6%)
Other domains (9%)
A structured study plan is recommended for navigating this material, utilizing the official ISA study guide and practice tests. Candidates should concentrate on the highest-weighted domains while ensuring a foundational understanding of all sections. The exam is available year-round through computer-based testing centers or through select paper-based events hosted by local ISA chapters.
Maintaining Your Professional Credentials
Achieving the Certified Arborist designation requires dedication to ongoing learning and adherence to a recertification cycle. The credential is valid for three years, after which the arborist must demonstrate continued competence to maintain status. The primary method for recertification is the accumulation of 30 Continuing Education Units (CEUs) tracked throughout the three-year period.
Earning 30 CEUs qualifies the arborist for renewal without retaking the full certification examination. CEUs can be obtained through professional development activities, such as attending educational workshops, participating in seminars, or completing approved online courses. The recertification process also involves paying a renewal fee, discounted for ISA members, and reaffirming adherence to the ISA Code of Ethics. Failing to meet the CEU or fee requirements necessitates retaking the comprehensive examination.
State and Local Licensing Requirements
The ISA Certified Arborist credential does not automatically grant the legal authority to operate a tree care business in all locations. State and local jurisdictions impose separate, mandatory licensing requirements focused on consumer protection and business regulation. These government-issued licenses frequently necessitate proof of adequate general liability insurance and workers’ compensation coverage, along with a surety bond to protect customers in the event of property damage or incomplete work.
Several states have specific arborist licensing programs that go beyond general business registration, sometimes requiring a separate examination to practice within their borders. States like Maine, New Jersey, and Louisiana require a state-issued license for anyone performing arborist services for hire. In Maine, an ISA Certified Arborist may be exempted from taking the state exam but must still complete the application process and provide proof of insurance.
Any professional intending to apply chemical treatments, such as insecticides, fungicides, or herbicides, must obtain a separate commercial pesticide applicator license. This license is typically issued by the state’s department of agriculture or environmental protection. Because requirements are highly variable, aspiring arborists must thoroughly research the specific ordinances and licensing boards in their intended state, county, and municipality before engaging in commercial tree care operations. The ISA certification must be supplemented with appropriate local licenses to ensure full legal compliance.