- This paper presents the psychometric properties of the MoMo-AFB (Bos, Worth, Opper, Oberger & Woll, 2009), a questionnaire designed to measure the physical activity of children and adolescents. The MoMo-AFB consists of 28 items, covering the fields of everyday physical activity, sports within and outside of organised clubs, physical education as well as compliance with physical activity guidelines. A study was conducted with 109 boys and 87 girls aged between 9 and 17 years. The MoMo-AFB was given on two separate occasions to evaluate reliability and was compared with accelerometry data of ActiGraph GT1X to evaluate validity. The overall kappa/weighted kappa coefficient for the one-week testretest reliability was .66 (SD = .19) and the overall intraclass correlation (ICC) .68. Self-reported and accelerometer-measured average weekly time spent performing moderate to vigorous physical activity were significantly correlated (Spearman r = .29). Regarding reliability and validity, the MoMo-AFB is comparable with other internationalThis paper presents the psychometric properties of the MoMo-AFB (Bos, Worth, Opper, Oberger & Woll, 2009), a questionnaire designed to measure the physical activity of children and adolescents. The MoMo-AFB consists of 28 items, covering the fields of everyday physical activity, sports within and outside of organised clubs, physical education as well as compliance with physical activity guidelines. A study was conducted with 109 boys and 87 girls aged between 9 and 17 years. The MoMo-AFB was given on two separate occasions to evaluate reliability and was compared with accelerometry data of ActiGraph GT1X to evaluate validity. The overall kappa/weighted kappa coefficient for the one-week testretest reliability was .66 (SD = .19) and the overall intraclass correlation (ICC) .68. Self-reported and accelerometer-measured average weekly time spent performing moderate to vigorous physical activity were significantly correlated (Spearman r = .29). Regarding reliability and validity, the MoMo-AFB is comparable with other international published physical activity questionnaires for adolescents.…