The Y-BOCS measures the severity of obsessive-compulsive symptoms independently of their content. A clinician first establishes which symptoms are present using a separate symptom checklist, then rates ten severity items in a semi-structured interview: five for obsessions and five for compulsions. Each item is scored 0 to 4, giving obsession and compulsion subtotals of 0–20 each and a total of 0–40.
The five parameters are rated in parallel on both sides: how much time the symptoms occupy, how much they interfere with functioning, how much distress they cause, how much the patient resists them, and how much control the patient has over them. Because severity is scored separately from symptom content, the total is comparable across patients whose presentations look nothing alike; a contamination presentation and a checking presentation with the same total carry a similar burden.
02 - Origin & purpose
Where it comes from.
Goodman, Price, Rasmussen and colleagues published the Y-BOCS in 1989 in Archives of General Psychiatry, in two papers: the first covering development and reliability, the second validity. The design problem they set out to solve was that existing measures conflated how many symptoms a patient had with how severe they were, which made treatment effects hard to read in patients whose symptom content shifted.
The scale became the standard primary outcome measure in OCD treatment trials and has held that position since. A revision, the Y-BOCS-II (Storch et al., 2010), extends each item to a 0–5 range for a total of 0–50, folds avoidance into the severity ratings and replaces the resistance-to-obsessions item. A paediatric version, the CY-BOCS (Scahill et al., 1997), follows the same architecture for children and adolescents.
03 - Scoring & cutoffs
How scoring works.
The rater sums the ten severity items for a total of 0–40. The conventional severity bands, published by the scale's rights holder, are 0–7 subclinical, 8–15 mild, 16–23 moderate, 24–31 severe and 32–40 extreme. Trials typically require a baseline total of 16 or above for entry.
Two cautions. First, the conventional bands are widely cited to the 1989 papers but we have not been able to confirm that they originate there; treat them as the developers' guidance rather than an empirically derived classification. Storch and colleagues (2015) derived bands empirically against clinician global impressions in 954 patients and arrived at different boundaries: 0–13 mild, 14–25 moderate, 26–34 moderate-to-severe, 35–40 severe, which places a total of 20 in a different band from the conventional scheme. Second, the Y-BOCS-II runs 0–50 and its scores must not be read against 0–40 bands.
Score
Severity
Interpretation
0–7
Subclinical
Symptoms present but below the threshold at which treatment trials recruit.
8–15
Mild
Mild obsessive-compulsive symptoms.
16–23
Moderate
Moderate symptoms. The conventional threshold for treatment-trial entry is 16.
24–31
Severe
Severe symptoms with substantial functional interference.
32–40
Extreme
Extreme symptoms. Intensive treatment is usually indicated.
04 - Validation evidence
How well it performs.
The strongest evidence comes from a reliability generalisation meta-analysis by López-Pina and colleagues (2015), which screened 11,490 studies and pooled 144. Across those studies the total scale showed mean internal consistency of α = 0.87, mean test-retest reliability of r = 0.85, and a mean inter-rater ICC of 0.92. For a clinician-rated interview, that is a strong profile, and it is the main reason the Y-BOCS has resisted replacement.
The factor structure is less settled. Competing models place the items on an obsessions-versus-compulsions split, on a severity-versus-resistance split, or on three factors. Storch and colleagues (2010) found that confirmatory analysis did not adequately fit any previously published model, and their exploratory analysis recovered two factors broadly matching obsessions and compulsions. Deacon and Abramowitz (2005) argued for deleting the resistance and control items on psychometric grounds.
0.87
Pooled Cronbach's α
Mean internal consistency across 144 pooled studies (López-Pina et al., 2015)
0.92
Inter-rater ICC
Mean inter-rater reliability across pooled studies
0.85
Test-retest
Mean test-retest reliability across pooled studies
6 pts
Minimal important difference
Or a 25% improvement, from 2,136 patients (Cervin et al., 2025)
05 - How it compares
How it compares to the alternatives.
Instrument
Items
Time
When to reach for it
Y-BOCS
10 scored (0–40)
~30–45 min with checklist
The standard clinician-rated severity measure and trial endpoint. Licensed; requires permission.
Y-BOCS-II
10 scored (0–50)
~30–45 min
The revision: avoidance integrated, resistance item replaced. Do not compare its totals to 0–40 bands. Same licence.
The paediatric equivalent, for children and adolescents. Same licensing position.
06 - When to use it
Right tool, wrong tool.
The Y-BOCS is the reference standard for grading OCD severity once the diagnosis is established. It is an interview, not a screen, and it is licensed, so the practical question is when it earns its time and its licence fee.
Reach for it when
-Grading OCD severity in a specialist setting where a trained rater and interview time are available
-Measuring treatment response over a course of exposure and response prevention or pharmacotherapy
-Producing an outcome that can be compared against the OCD trial literature
-Assessing a patient whose symptom content changes over time, since severity is rated separately from content
Reach for something else when
-You need a screening instrument - the Y-BOCS assumes OCD is already suspected or diagnosed. Use the DOCS or OCI-R
-No licence is in place - the instrument cannot lawfully be reproduced or digitised without permission
-Interview time is not available; a self-report measure will give you more usable data than a rushed interview
-The patient is a child or adolescent - use the CY-BOCS
-The presentation is primarily hoarding, which is now a separate diagnosis and is better measured with a hoarding-specific instrument such as the Saving Inventory-Revised
07 - Confidence & precision
Reading the score with care.
No standard error of measurement for the Y-BOCS is established in the literature, so we do not quote one. What is well established is how much change matters. Cervin and colleagues (2025) analysed 2,136 patients and put the minimal clinically important difference at 6 points, or a 25% improvement, with the raw threshold varying by baseline severity: around 8 points for severe presentations, 6 for moderate and 4 for mild. An earlier estimate from SSRI trials put it at 4.9 points (95% CI 4.4–5.4).
The international expert consensus (Mataix-Cols et al., 2016) defines treatment response as a reduction of 35% or more together with a CGI-Improvement rating of 1 or 2 sustained for at least a week, partial response as a 25–34% reduction, and remission as a total of 12 or below with a CGI-Severity of 1 or 2. Older conventions using a 25% reduction for response and 14 for remission remain in circulation; say which you are applying.
One rating quirk is worth knowing. The resistance items behave paradoxically after exposure and response prevention, because patients are explicitly taught not to resist their obsessions; the resistance-to-obsessions item had the weakest relationship with the rest of the scale and was replaced in the Y-BOCS-II for this reason.
08 - Limitations
What it cannot tell you.
The Y-BOCS is a severity measure, not a diagnostic instrument or a screen; it presupposes that OCD has already been identified. It requires a trained rater and a substantial interview, which puts it out of reach for most routine practice. Its factor structure does not replicate reliably, so subtotals should be read cautiously. The resistance and control items are psychometrically the weakest and are actively misleading in patients who have completed exposure and response prevention. Severity bands differ between the developers' conventional scheme and empirically derived alternatives. Hoarding, now classified separately from OCD, is not well served by it. And because the instrument is licensed, most clinics cannot lawfully digitise it into their record system without a paid agreement.
09 - Licensing, explained
How licensing works.
The Y-BOCS, Y-BOCS-II, CY-BOCS and the self-report variants are the intellectual property of OCD Scales, LLC, and are registered trademarks. That is why you will not find the interview on this page.
The rights holder's stated position is that non-commercial clinical and research use of the paper forms requires written approval from the authors, and that any commercial use, including digitising the form, embedding it in an electronic record, building it into an app, or using ambient AI during administration to produce a digital record, requires a paid licensing agreement. Translations and adaptations require prior authorisation, and publishing or posting the scales online is not permitted. There is no free version of the Y-BOCS itself.
One related measure is more permissive: the DSM-5 Level 2 measure for repetitive thoughts and behaviours, adapted from the FOCI severity scale, may be reproduced in paper form by clinicians for use with their own patients, though electronic use still requires written permission. Note that the FOCI itself sits inside the OCD Scales portfolio and is not a free alternative.
If you need something you can score today, the DOCS is the strongest genuinely free self-report option: it is distributed at no charge by its author and outperformed the OCI-R on diagnostic accuracy in the original validation.
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