The strengths and difficulties questionnaire (SDQ) is a frequently used tool for universal screening of pre-schoolers’ behavioural and emotional problems. However, evidence for its concurrent validity is equivocal and has not been tested in a Māori population. We aimed to evaluate the concurrent validity of the strengths and difficulties questionnaire (SDQ) in Māori pre-schoolers (tamariki), aged 4 and 5. We carried out a prospective study of 225 tamariki (46% female) for whom a recent SDQ was available from the New Zealand Ministry of Health’s Before School Check database. A trained nurse carried out a standardised wellbeing and behavioural assessment for these children. Sensitivity, specificity, positive predictive and negative predictive values were calculated, using optimal total difficulty scale threshold values published for the SDQ (parent version SDQ-P; teacher version SDQ-T). Primary outcome: an assessment-based child referral to Child and Adolescent Mental Health Services or to a Paediatric outpatient service. Secondary outcomes: assessment-based parental referral to a parenting programme and combined referral. The optimal thresholds for child referral were low for the SDQ-P (13) and SDQ-T (7). Child referral SDQ-P: sensitivity 62%, specificity 83%, positive predictive value 0.35, negative predictive value 0.94. Child referral SDQ-T: sensitivity 77%, specificity 78%, positive predictive value 0.31, negative predictive value 0.96. The findings demonstrate optimal threshold values for referral for Māori on the SDQ-P and SDQ-T are much lower when compared to published thresholds (17 vs. 16). Sensitivity values were also low. A surveillance approach for the assessment of psychosocial problems is recommended for pre-schoolers.