"The Conners" is not a single questionnaire but a family of ADHD rating scales published by Multi-Health Systems (MHS). The Conners 3 (2008) assesses ADHD and common comorbid problems in children and young people aged 6 to 18, with parallel parent, teacher and self-report forms covering inattention, hyperactivity/impulsivity, learning problems, executive functioning, defiance/aggression and peer relations. The Conners Adult ADHD Rating Scales (CAARS, 1999; CAARS 2, 2023) cover adults, with self-report and observer forms.
All Conners instruments convert raw scores to T-scores normed by age and sex (mean 50, SD 10). They are dimensional severity measures used to support, not to make, an ADHD diagnosis, and to monitor symptom change during treatment.
02 - Origin & purpose
Where it comes from.
C. Keith Conners published his first teacher rating scale for hyperkinetic children in 1969, one of the earliest standardised ADHD measures. The scales have been revised repeatedly since: the Conners Rating Scales-Revised in 1997, the Conners 3 in 2008, the CAARS in 1999 and the CAARS 2 in 2023.
Their purpose is multi-informant assessment, combining parent, teacher and self-report so symptoms are captured across settings as DSM-5 criteria require. They are widely used in schools, in paediatric and adult ADHD services, and as outcome measures in clinical trials.
03 - Scoring & cutoffs
How scoring works.
Raw item responses (a 0 to 3 Likert scale) are summed by subscale and converted to age- and sex-normed T-scores. The usual interpretation conventions are: below 60, within the normal range; 60 to 64, elevated and a borderline concern; 65 to 69, elevated and clinically meaningful; 70 or above, markedly atypical.
Scoring requires the MHS norm tables, software or scoring service. This is part of what the licence pays for, and it is why raw-score cutoffs cannot be published here.
04 - Validation evidence
How well it performs.
Normative samples run to several thousand ratings per informant form according to the MHS manuals. Independent validations across languages broadly replicate the reliability figures, with more variable findings for factor structure.
0.94
CRONBACH'S α (CONNERS 3 PARENT)
0.90
TEST–RETEST ICC (CONNERS 3)
0.86–0.92
CAARS-S:L INTERNAL CONSISTENCY
0.93 · 93% · 70%
AUC / SENS / SPEC (CONNERS 3)
05 - How it compares
How it compares to the alternatives.
Instrument
Items
Time
When to reach for it
Conners
Varies by form
~10–20 min
Licensed, multi-informant, age- and sex-normed T-scores. Strong psychometrics, but requires an MHS licence and scoring service.
-Services without an MHS licence: use Vanderbilt or SNAP-IV for children, ASRS-5 for adults.
-Diagnosis on its own: no rating scale substitutes for a clinical interview.
-Retrospective adult assessment of childhood symptoms: use the WURS-25.
07 - Confidence & precision
Reading the score with care.
The T-score metric implies a standard error of measurement of roughly 3 to 5 T-points on most content scales, given reliabilities above 0.85, so single-scale changes under about 5 T-points should not be over-interpreted. No universally accepted minimal clinically important difference has been established for Conners T-scores. Cross-informant discrepancies are expected: parent and teacher agreement is typically modest, and is better read as information about setting-specificity than as error.
08 - Limitations
What it cannot tell you.
A commercial licence is required and there is a per-form cost. Item content cannot be reproduced or self-hosted, which is why no items or calculator appear on this page.
Informant agreement is modest, and the norms are North American, so T-scores may miscalibrate in other populations. The full-length forms are lengthy. Successive revisions (Conners 3 to Conners 4, and CAARS to CAARS 2) also complicate longitudinal comparison across editions.
09 - Licensing, explained
How licensing works.
The Conners scales are published and licensed by Multi-Health Systems (MHS). Use requires purchasing the forms and scoring, so no items or interactive calculator can be offered here.
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