CTW Exam Domains 2026: Complete Guide to All 5 Content Areas

The Five-Domain Blueprint at a Glance

If you are preparing for the ISA Certified Tree Climber credential (formerly titled ISA Certified Tree Worker Climber Specialist), the single most useful document you can read is the official examination outline. It tells you what the written exam tests and how heavily each area counts. The current outline, the 2024 file built on ISA's 2022 job-task analysis, divides the written exam into five weighted domains that total 100%.

Notice that the domains are numbered in the order ISA lists them, not by weight. Pruning (Domain 5) actually outweighs Tree Identification and Health (Domain 4) by a factor of two, so do not let the numbering mislead your study priorities. Safety, Climbing and Rigging, and Removal together account for 70% of the written exam, which tells you the credential is fundamentally about doing dangerous work correctly.

How the Written Exam Is Built

Before diving into individual domains, it helps to understand the container they live in. The written component is a closed-book, computer-based test delivered at Pearson VUE testing centers. ISA Certification Partners can also arrange paper written examinations. Phones and reference materials are prohibited, and any break you take counts against your time. A remote-proctored route was not verified in the sources we reviewed, so plan on a testing-center visit.

Question count and the unscored pretest items

The written exam contains 65 multiple-choice questions, each with four options and one correct answer. Of those 65, 15 are unscored pretest items that ISA uses to evaluate future questions. That leaves 50 scored questions. The 15 are included within the 65, not added on top, a point some third-party sites get wrong. You will not know which items are unscored, so treat every question as if it counts.

You have 90 minutes for the written component. That works out to a bit under 1.4 minutes per question across all 65, which is comfortable for well-prepared candidates but tight for anyone who has to reason through unfamiliar rigging calculations from scratch.

Passing criteria

You need at least 80% on the written exam and at least 70% on the skills assessment, with a minimum of 27 of 38 skills points and every critical requirement satisfied. Passing both components is required unless an approved exception applies. For a full breakdown, see CTW Passing Score 2026: Exactly What You Need to Pass. ISA does not publicly disclose an aggregate pass rate in the sources we reviewed, so be skeptical of any site quoting a failure percentage; our CTW Pass Rate 2026: What the Data Shows article explains what can and cannot be said.

Domain 1: Safety (26%)

Safety is the heaviest domain, and it deserves the most study time. More than a quarter of your scored written questions come from here, and safety judgment also threads through every other domain, because a rigging or removal question will often have a "safest correct answer" built into it.

The safety domain also explains one of the credential's prerequisites. Applicants must show current hands-on CPR and first-aid training and physical aerial-rescue training completed within the preceding year. ISA is signaling that safety knowledge must be practiced, not merely memorized. Our CTW Requirements 2026: Eligibility, Prerequisites & How to Qualify guide covers the documentation in detail.

Domain 2: Tree Climbing and Rigging (22%)

This domain covers how you move in the tree and how you manage loads. It is one of two 22% domains and, for working climbers, usually feels like home turf, though the written phrasing can still trip up experienced people who learned their craft through habit rather than terminology.

Candidate discussions frequently ask about MRS versus SRS, which signals that people want a clear explanation of the climbing-system concepts behind the exam. In the written domain this appears as understanding what each system is, how it behaves, and what makes a given choice sound. Treat it as a reasoning topic rather than a brand-of-gear topic.

Domain 3: Tree Removal (22%)

Removal ties with Climbing and Rigging at 22%. It is where climbing technique, rigging, felling or sectioning decisions, and safety all converge. Many wrong answers on this domain are wrong because they ignore a hazard the question quietly planted in the scenario.

Because removal questions are so scenario-driven, a practice bank that mirrors this style is far more valuable than flashcards of definitions. Our practice test site is built around exactly that kind of applied question, mapped to the weighted areas.

Domain 5: Pruning (20%)

Pruning carries 20%, making it the fourth-heaviest domain and far more than a side topic. Candidates who come from removal-heavy work sometimes underprepare here and lose avoidable points.

Pruning knowledge overlaps with the identification and health domain, because good pruning decisions depend on understanding species tendencies and tree condition. Study the two together.

Domain 4: Tree Identification and Health (10%)

Although this is the smallest domain at 10%, it is not one to skip. Roughly one in ten scored items comes from here, and a handful of questions can be the difference when the written bar is 80%.

Unlike the other four domains, much of this content depends on your local region's species, so supplement general study with attention to the trees you actually encounter. The official Tree Climbers' Guide, Fourth Edition (2021), is a preparation publication, but ISA states that the book and the certification exams are developed through separate processes. It is a useful resource, not a substitute for the official outline.

Written Domains vs. the Outdoor Skills Assessment

One of the most common sources of confusion is treating the five domains as if they also describe the practical test. They do not. The outdoor skills assessment is evaluated against a separate form, and it measures physical competency in ways that no quiz score can.

How the climb is timed

On the skills side, the clock starts on the first rope throw. Exceeding the 30-minute full-credit target incurs a three-point timing deduction, and exceeding 45 minutes fails the task. Equipment inspection and the six knot demonstrations are separate from the timed climb. Notably, one older training page still cites a 30-minute practical limit, which conflicts with the current 45-minute maximum, so verify timing against the current evaluation form rather than a chapter summary.

Competition-based waivers

Some candidates ask whether competing in a tree climbing championship lets them skip the skills test. An approved competition-based waiver applies only to the work-climb portion. Completion of all specified TCC/ITCC events, gear inspection, the six knots, and evaluator documentation is still required, so it is not a blanket exemption from skills requirements.

For how hard each component tends to feel, see How Hard Is the CTW Exam? Complete Difficulty Guide 2026.

Why Older Eight-Domain Summaries Are Out of Date

If you have searched around, you may have found pages describing eight content areas, or a 30-minute practical limit. The current official scheme is five domains. An eight-domain reference lingers in some renewal prose and older chapter summaries, but it is inconsistent with the current outline. The issuer's change notice also contains an internal date inconsistency, naming May 1, 2024 in its narrative but January 1, 2024 in a table heading, so we describe the five-domain structure as the current scheme rather than pinning it to a single effective date. The August 2025 program guide establishes the current five-domain scheme.

The practical lesson: when two sources disagree about domains, weights, timing, or fees, trust the current ISA outline and program guide over training pages, forums, or third-party question banks. This applies to the exam format too. Some sites describe 65 scored questions plus 15 unscored ones, which is incorrect; the correct figure is 65 total with 15 unscored inside it.

Sequencing Your Study Around the Weights

You do not need an elaborate method, only a schedule that spends time in proportion to the weights and respects how the domains reinforce each other. Here is one sensible sequence, with the reasoning built in.

For a one-page recap to use near exam day, see the CTW Cheat Sheet 2026: One-Page Review of Must-Know Facts, and check scheduling details in CTW Exam Dates 2026: Testing Windows, Deadlines & Scheduling.

Money and payoff, briefly

Fees matter when you plan your timeline. The application fee is $40 for ISA members or current credential holders and $50 for others, plus enrollment. The issuer's own documents conflict on enrollment: the August 2025 Program Guide and Exam Information page list $369, while the Common Questions table says $396, and we retain that unresolved conflict rather than choosing one. Retakes are $120 after a required 30-day wait. See CTW Certification Cost 2026: Complete Pricing Breakdown for the full picture. On earnings, occupational wage data (a 2025 median of $50,960 per year for tree trimmers and pruners) describes the occupation, not certified-climber pay, and no universal credential premium was verified. Dated employer examples exist, such as a $325 monthly supplement in a 2024 Glendale recruitment, but they are employer-specific. Our Is the CTW Certification Worth It? Complete ROI Analysis 2026 explores this honestly.

Frequently Asked Questions

Ready to test yourself against the weighted domains? Work through original scenario questions on our CTW practice test and track your results domain by domain.