Abstract Background: Networks with closed structures may lead to a scarcity of diversified norms which may leave an individual with only negative norms to be influenced by. Trust, relationship quality and social support are also examples of characteristics which may affect the adoption of health behaviors.                                                                                           Aims: To study whether there are any associations between network closure as well as relationship content (trust, relationship quality, social support) and the use of cannabis as well as the frequency of binge drinking, and how these associations are interacted by other factors.  Method: Logistic regression analyses were carried out to calculate the crude and adjusted odds ratios for 19-years old young adults in Sweden (n=2,942). Interaction analyses were also performed.                                                                                                                          Results: Individuals in high closure networks had a higher tendency to binge drink frequently. Individuals that in general are unhealthy, have many smoking friends and who are males had a higher propensity to both use cannabis and to binge drink when included in high closure networks.                                                                                                                      Conclusion: Individuals may be affected negatively by being included in networks with closed structures – some more than other − which is possibly mediated by the types of norms that are available.