ISA Certified Arborist

When you become an ISA Certified Arborist®, you are recognized by your peers and the public as a tree care professional who has attained a generally-accepted level of knowledge in areas such as tree biology, diagnosis, maintenance practices, safety, and other subject and practice areas within the tree care profession as identified through periodic job task analyses.

Prerequisites for this certification:

  • Minimum of three (3) years in the field or two (2) years with a two (2) or four (4) year degree in a related field

Examples of experience sources include, but are not limited to:

  • Tree care companies
  • Nurseries
  • Landscape companies
  • Municipalities
  • State forestry agencies
  • Utility companies
  • Academic arboriculture/horticulture departments (for instructors)
  • Horticulture/extension programs (for advisors)
  • Consultancies
  • Pest control providers

IAA offers workshops to help prepare you for the exam. Typically, classes run for one 2.5 hour night per week for nine weeks with the exam on the last night of class. Class is taught from the Arborist Certification Study Guide and the ANSI Z-133 Safety Standards. We also offer these classes in Spanish. Classes run in the spring and in the fall, check the website calendar for upcoming classes – both in person and virtual.

Follow this link to purchase a copy of the Arborist Certification Study Guide: and Spanish copy:

Follow this link to purchase a copy of the ANSI Z-133 Safety Standards: and Spanish copy:

The examination is made up of 200 multiple-choice questions. Each question has four possible answers listed, only one of which is correct. You will have 3.5 hours (210 minutes) to complete the written exam. You must pass the exam to obtain the certification.

The written exam content is divided into 10 areas of knowledge, and the percentage next to each area below reflects the percentage of questions associated with that area.

  1. Soil Management—12%
  2. Identification and Selection—8%
  3. Installation and Establishment—5% 4. Safe Work Practices—15%
  4. Tree Biology—8%
  5. Pruning—16%
  6. Diagnosis and Treatment—12%
  7. Urban Forestry—7%
  8. Tree Protection—4%
  9. Tree Risk Management—13%

If you do not pass the exam, you are allowed one free retake.

Certification is valid for 3 years. To retain certification after each three-year period, an ISA Certified Arborist® must recertify. The ISA Certification Program offers two methods of recertification. The first method is to retake and pass the certification exam again. The second option is to accumulate at least 30 continuing education units (CEUs) over the three-year certification period that are related to the 10 tested domains on the exam and pay the recertification fee.

Exam application provides more details on the certification. Follow this link to the exam application: