The positive mental health and well-being perspective represents innovative public health research of first-rank priority in Europe. Good mental health is both a state and a resource for everyday life. Hence, the concept often refers to a subjective feeling (hedonic component) as well as positive functioning (eudaimonic component). Different conceptualisations of mental health-related issues are a background to this paper, which gives a brief overview of three research issues in the Nordic countries. First, the development in the occurrences of adolescent mental health-related indicators such as life satisfaction, health, sleep, and school pressure. Second, review of Nordic methodological studies reporting on different mental health-related measures. Third, the selection of measures of positive mental health employed in the 2017-2018 Health Behaviour among School-aged Children (HBSC) data collection in the Nordic countries. Using the Nordic HBSC data for 2002-2014, it was found that symptom and problem-oriented analyses of mental health can improve our understanding of the challenges adolescents face. However, there is also a need to examine positive aspects of mental health in order to enhance our understanding of different mental health-related dimensions. New measures were included in the 2017-18 HBSC data collection in the Nordic countries, enabling researchers to answer different research questions including analysing factors mediating and moderating positive mental health among school-aged children. Extending the perspective from a symptom-and problem-oriented view to a more positive and asset-based perspective adds additional value to studies of mental health.