- Which Credential This Sheet Covers
- Exam Snapshot: Format and Scoring Numbers
- The Five Written Domains at a Glance
- Skills Assessment: Inspection, Knots, and the Climb
- Eligibility and Application Checklist
- Fee Table, Including the Conflicting Price
- Pay and Value: What Is and Isn't Verified
- Tree Climber vs. Arborist vs. European Reciprocity
- Renewal Rules in Brief
- A Domain-Weighted Review Schedule
- Frequently Asked Questions
- The written exam has 65 questions in 90 minutes, and 15 of those are unscored pretest items.
- Passing requires at least 80% on the written exam and 70% on skills, with every critical requirement met.
- Safety is the heaviest written domain at 26%; Climbing/Rigging and Removal are 22% each.
- Enrollment is listed at $369 in some ISA sources and $396 in others, so confirm before paying.
Which Credential This Sheet Covers
This page reviews the ISA Certified Tree Climber, issued by the International Society of Arboriculture (ISA). Many candidates still search for the older name, Certified Tree Worker Climber Specialist. ISA's 2023 Annual Report confirms that credential was renamed ISA Certified Tree Climber in 2023, so the two names point to the same certification. ISA's own abbreviation is CTC; this site uses "CTW" as its label for the credential. For background on the naming, see What Is CTW Certification? and What Does CTW Stand For?
The credential has two parts: a closed-book written exam and a hands-on outdoor skills assessment. Both must be passed. Everything below is organized so you can scan it in a few minutes and then follow the links for depth.
Exam Snapshot: Format and Scoring Numbers
| Item | What to Know |
|---|---|
| Written format | 65 multiple-choice questions, four options each, one correct answer |
| Scored vs. unscored | 15 of the 65 are unscored pretest items, leaving 50 scored |
| Written time | 90 minutes; breaks count against your time |
| Written passing | At least 80% |
| Skills passing | At least 70%, with a minimum of 27 of 38 points and all critical requirements satisfied |
| Delivery | Computer-based at Pearson VUE testing centers; paper exams and skills assessments arranged through ISA Certification Partners |
| Languages | English, Japanese, Spanish, Traditional Chinese |
| Validity | Three years |
The written exam is closed-book. Phones and reference materials are prohibited. A remote-proctored route was not verified, so plan on a testing center. For how the scoring thresholds play out in practice, read CTW Passing Score 2026: Exactly What You Need to Pass.
The Five Written Domains at a Glance
The current written exam is built on five weighted domains from ISA's examination outline (the 2024 file, based on the 2022 job-task analysis). Some older chapter summaries and training pages still describe an eight-domain structure; that is outdated. These weights describe written-exam objectives only. They are not the allocation of skills-test points, and they do not map one-to-one onto study-book chapters.
| Domain | Weight | Rough Share of 65 Items* |
|---|---|---|
| Safety | 26% | About 17 |
| Tree Climbing and Rigging | 22% | About 14 |
| Tree Removal | 22% | About 14 |
| Pruning | 20% | About 13 |
| Tree Identification and Health | 10% | About 6 or 7 |
*Illustrative arithmetic only (weight times 65). ISA does not publish exact item counts per domain, and pretest items are mixed throughout.
Safety (26%)
The largest slice, and the one that overlaps most with the skills test.
- Personal protective equipment and worksite hazard recognition
- Emergency planning, including aerial rescue readiness
- Safe operation around hazards such as electrical conductors
- Equipment condition and retirement judgment
Tree Climbing and Rigging (22%)
Climbing systems, anchor choices, and moving loads safely.
- Climbing system components and how they work together
- Knots, hitches, and when each is appropriate
- Rigging fundamentals for lowering and controlling loads
Tree Removal (22%)
Planning and executing removals while managing forces and targets.
- Assessing the tree and site before cutting
- Felling and sectional dismantling concepts
- Controlling pieces during rigging operations
Pruning (20%)
Cut types, objectives, and tree response.
- Proper cut placement and pruning terminology
- Matching pruning objectives to tree condition
- Working from the climbing line while pruning
Tree Identification and Health (10%)
The smallest domain, but easy points if you study it.
- Recognizing common species and basic biology
- Spotting structural defects and signs of decline that affect climb safety
Safety, Climbing/Rigging, and Removal together make up 70% of the written exam, so they deserve the bulk of your attention. A deeper domain-by-domain walkthrough is in CTW Exam Domains 2026: Complete Guide to All 5 Content Areas.
Skills Assessment: Inspection, Knots, and the Climb
The outdoor skills assessment is separate from the written exam and is scored on its own. The 2024 Skills Test Evaluation Form defines the structure, and it rewards preparation you can only get by actually climbing.
The pieces that are not on the clock
- Equipment inspection: you demonstrate how you check your gear before use. Compliant climbing equipment is required.
- Six knot demonstrations: the form allows one minute per knot.
The timed climb
- The maximum climb time is 45 minutes, and the clock starts on the first rope throw.
- The target for full credit is 30 minutes. Exceeding it costs a three-point timing deduction.
- Exceeding 45 minutes fails the task.
The evaluation form also defines critical failures and covers movement, descent, and work-station tasks, including MRS and SRS-related items. A critical failure sinks the assessment regardless of your point total, which is why the 27-of-38 minimum is only half of the pass condition. Strong written scores do not demonstrate climbing competence, so treat a practice quiz result as a knowledge check only. For a candid look at difficulty, see How Hard Is the CTW Exam? Complete Difficulty Guide 2026.
Competition-based waiver, precisely
ISA accepts an approved competition-based waiver, but it addresses the work-climb portion only. You must still complete all specified TCC/ITCC events, the gear inspection, the six knots, and the evaluator documentation. It is not a blanket exemption from the skills requirements.
Eligibility and Application Checklist
- Experience: at least 18 months of arboricultural climbing experience, documented with appropriate employer evidence.
- Self-employed applicants: submit three references, which can be dated invoices, contracts, or business licenses showing the climbing work.
- Training currency: hands-on CPR/first-aid training and physical aerial-rescue training completed within the preceding year.
- Ethics: agree to ISA's ethics and credentialing requirements.
- Apply and enroll: submit the application and enrollment fees to ISA.
- Schedule: once authorized, you have a 120-day window to test at Pearson VUE. Bring two identification documents whose names match your application.
No mandatory degree or fixed training-hour total was verified. Note the distinction between enrolling in a training course (a regional arborist association class, for example) and applying for the ISA exam: course enrollment does not register you for the credential. Full details are in CTW Requirements 2026: Eligibility, Prerequisites & How to Qualify, and scheduling specifics are in CTW Exam Dates 2026: Testing Windows, Deadlines & Scheduling.
Fee Table, Including the Conflicting Price
| Fee | Amount (USD) | Notes |
|---|---|---|
| Application | $40 or $50 | $40 for ISA members/current ISA credential holders; $50 for others |
| Enrollment (discounted group) | $295 | Applies to the discounted group |
| Enrollment (standard) | $369 or $396 | ISA's August 2025 Program Guide and Exam Information page say $369; the Common Questions table says $396 |
| Retake | $120 | After the required 30-day wait |
| Reciprocity (EAC European Tree Worker climbing holders) | $220 | Separate application with verification |
For budgeting scenarios, see CTW Certification Cost 2026: Complete Pricing Breakdown.
Pay and Value: What Is and Isn't Verified
No national salary estimate specific to certified tree climbers was verified, and no market-wide causal earnings effect was established. What can be said:
- Occupation-wide wages: O*NET/BLS reports a 2025 median of $24.50 per hour ($50,960 per year) for Tree Trimmers and Pruners. These figures describe the occupation, not credential holders specifically.
- Employer-specific incentives (dated examples): a City of Glendale Senior Tree Trimmer recruitment (open June 17 to July 12, 2024) advertised a $325 monthly supplement for ISA Certified Tree Climber. A City of Chico certification pay form (revised February 2022) lists $25 per month for the legacy Climber Specialist credential.
Those two examples show how widely municipal incentives can differ, and neither is a verified current offer. If a posting mentions certification pay, read it closely. Pass-rate claims deserve the same caution: ISA does not publicly disclose an aggregate pass rate in the sources reviewed, and third-party failure percentages are unsupported. See CTW Pass Rate 2026: What the Data Shows, CTW Salary Guide 2026: Complete Earnings Analysis, and Is the CTW Certification Worth It? Complete ROI Analysis 2026 for the full picture.
Tree Climber vs. Arborist vs. European Reciprocity
| Credential | Core Focus | Key Difference |
|---|---|---|
| ISA Certified Tree Climber | Safe, efficient aerial work: climbing, rigging, removal, pruning | Includes a hands-on skills assessment alongside the written exam |
| ISA Certified Arborist | Broader tree care knowledge | A separate ISA credential with its own exam; not interchangeable with Tree Climber |
| EAC European Tree Worker (climbing) holders | European climbing credential | May apply through a separate reciprocity route ($220, with verification); it does not substitute for the Tree Climber credential |
Holding one does not satisfy the requirements for another, so do not assume exam content overlaps cleanly. Choose based on your actual job: if your day is spent in the canopy, Tree Climber is the direct fit.
Renewal Rules in Brief
- Certification lasts three years.
- Renew with 15 relevant CEUs or by retaking the certification examination.
- Either route requires current CPR, first-aid, and aerial-rescue evidence plus applicable fees.
- Base recertification is $220, with $95 for each additional credential where the multiple-credential policy applies.
- Excess CEUs do not carry forward.
Start collecting CEU documentation early in the cycle rather than scrambling in year three.
A Domain-Weighted Review Schedule
The only study framework worth using here is one that mirrors the blueprint: spend time where the points are, and keep rope-handling practice running alongside the reading.
Safety (26%)
- Review PPE, hazard recognition, and emergency/aerial-rescue concepts
- Refresh your hands-on CPR/first-aid and rescue training if it is nearing the one-year mark
Climbing and Rigging (22%)
- Study system components and knot selection
- Practice all six knots against a one-minute-per-knot pace
Tree Removal (22%)
- Work through site assessment and load-control scenarios
- Rehearse a timed climb with the 30-minute target in mind
Pruning (20%) and Identification/Health (10%)
- Review cut types and objectives; memorize defect and species cues
- Finish with mixed timed practice using the 90-minute written limit
For a broader plan, see the CTW Study Guide 2026: How to Pass on Your First Attempt, and for question practice organized by domain, use the CTW practice tests. ISA's Tree Climbers' Guide, Fourth Edition (2021), is a preparation publication, but ISA states that the book and the exams are developed through separate processes, so treat it as a study aid rather than an exhaustive map of exam content. If you want a structured training path, CTW Training outlines your options.
Frequently Asked Questions
Fifty. The exam has 65 multiple-choice questions in total, and 15 of them are unscored pretest items. You cannot tell which are which, so answer every question carefully.
Yes, unless an approved exception applies. You need at least 80% on the written exam and 70% on skills (minimum 27 of 38 points) with all critical requirements satisfied. A competition-based waiver covers only the work-climb portion.
The retake fee is $120, and you must wait 30 days before retesting. Ignore older or third-party figures that list a lower retake price.
Safety. At 26% it is the largest written domain, and it also supports the equipment-inspection and critical-failure expectations on the skills test. Climbing and Rigging and Tree Removal follow at 22% each.
Not in the issuer sources reviewed. Be skeptical of any site quoting a specific failure percentage; focus instead on the published passing criteria and your own readiness. More context is in CTW Certification.