OBJECTIVES:The aim of the present study was to examine the factor structure, model-based reliability, measurement invariance and concurrent validity of the five-item version of the Mindfulness Attention Awareness Scale (MAAS) in Norwegian adolescents. METHODS:An initial pilot study was carried out using a sample of 77 fifteen year olds. For the main analyses, a sample of 2140 Norwegian adolescents was used who participated in the cross-sectional Health Behaviour in School-Aged Children (HBSC) study. All participants were asked to complete a questionnaire. RESULTS:Confirmatory factor analyses found support for the one-factor structure of the five-item version of the MAAS. Acceptable model fit was found in both the pilot sample (χ2=6.48, df=5, p=0.26; root mean square error of approximation [RMSEA]=0.06; comparative fit index [CFI]=0.99; standardised root mean square residual [SRMR]=0.03) and the HBSC sample (χ2=27.1, df=4, p<0.001; RMSEA=0.05; CFI=0.99; SRMR=0.01). The model-based reliability of the scale was good (ω=0.84 and ω=0.81, respectively). Scalar measurement invariance was established for sex, age and material affluence. Finally, the five-item MAAS displayed concurrent validity through moderate negative associations with health complaints ( r=-0.44; p<0.001) and school stress ( b=-0.44, p<0.001), and a positive moderate correlation with life satisfaction ( r=0.26; p<0.001). CONCLUSIONS:The five-item version of the MAAS is an adequate measure of mindfulness in Norwegian adolescents. Due to the brief nature of the scale, it can easily be included in epidemiological and clinical studies with an interest for trait mindfulness. The five-item MAAS may therefore have great potential to facilitate more knowledge about the role of mindfulness in adolescent health.