The Strengths and Difficulties Questionnaire (SDQ) is a behavioural screening questionnaire developed specifically for children and adolescents. This paper presents SDQ scores for a sample of 484 New Zealand secondary school students aged 13-17 and examines the relationship between SDQ score, ethnicity, age, gender, and alcohol and cannabis use. We found that only 4% of our sample of secondary school students fell within the 'abnormal' range and that difficulties, as reported via the SDQ, appeared greater amongst younger adolescents (13-15 yrs) and did not vary by ethnicity. Our results support further validation of the SDQ within a random New Zealand community sample and suggest that practitioners should be cautious when interpreting SDQ symptom scores particularly in older adolescents.