Traditional Norwegian "friluftsliv" activities are closely related to traditional outdoor recreational activities existing worldwide. These activities are unique in that they tend to reach adolescents whom organized sports do not. Therefore, the Norwegian government has focused on traditional friluftsliv activities in its public health efforts. However, there is a paucity of knowledge in the extant literature regarding which factors predict inactivity in these activities and to what extent. To fill this gap, 557 Norwegian adolescents (ages 16-19 years) answered a questionnaire probing their activity levels in six traditional outdoor recreational activities, and 18 possible predictors of inactivity in these activities were examined. The main finding from the logistic regression analyses was that if the respondents reported that their family members were not active in a traditional outdoor recreational activity, the probability of being inactive increased dramatically. This prediction also applied to all six activities. The results indicate that the way youth think about their families in relation to traditional outdoor recreational activities profoundly affects the level of activity of youth in these activities.