ISA Certified Arborist Guide 2026

Three years of full-time practical experience in arboriculture, or a shorter period of experience combined with a degree in arboriculture, horticulture, forestry or landscape architecture. The experience requirement is what gives the credential its standing — there is no route straight from a classroom to certification.

A separate ISA qualification covering structured, defensible tree risk assessment: identifying targets, assessing likelihood of failure and consequences, and documenting the assessment. It is widely required in its own right for municipal and consulting work, and it is a qualification rather than a certification, with its own renewal cycle.

Thirty continuing education units over each three-year cycle, distributed across the credential's subject areas, or re-examination. Units come from ISA and chapter education, conferences, workshops and other approved activity. Most working arborists accumulate them through the training their employer or chapter already offers.

Rarely by state law — arboriculture is not licensed in most states, though tree care businesses and pesticide application may be regulated separately. The requirement usually comes from local tree ordinances, municipal and utility contracts and insurers, which frequently require a certified arborist to write reports, specify work or supervise crews.

Yes, within the safe work practices and climbing and work practices domains, alongside electrical hazard awareness and aerial rescue. But the examination spans the full scope of arboriculture — biology, soils, diagnosis, urban forestry and tree protection — so a strong climber who has not studied the science-side domains will struggle.