Mental health is a major child public health issue in Sweden. The overall aims of this thesis are to explore girls’ and boys’ perspectives on mental health and on mental health-promoting initiatives, and to deepen the knowledge of disclosure and support for ado-lescents at risk of abuse and neglect. Four studies are included in the thesis, and a qualitative descriptive design was chosen. In three of the studies (Studies I, II, and III), adolescents in Sweden were interviewed individually or in focus-groups. In the fourth study (IV) officials and politicians in nine municipalities in Sweden were interviewed, and documents were analysed in a multiple-case-study design. In study I the adolescents were asked about the mental health-promoting dialogue with the school nurse. The results reveal that what the adolescents found important were trustiness, attentiveness, respectfulness, authenticity, accessibility, and continuity. The adolescents also had certain views on what issues to talk about in the health dialogue; physical and psychological issues should be included. In Study II, the adolescents perceived “mental health” to be an emotional experience with positive and negative aspects of internal and relational feelings. Family, friends, and school were regarded as important determinants of mental health by the adolescents. Neither girls nor boys thought that there were any major differences in mental health between girls and boys, but did think they were subject to different expectations. In Study III the results show that adolescents with families with alcohol problems are unsure whether to disclose their home situation to an adult; the adolescents seem to make a risk assessment when looking for trustworthy adults. It is a disclosure process. Friends are confidants and supportive, and sometimes facilitators for contacting adults, when support from adults is needed. Study IV show that even small grants to municipalities for children-at-risk projects lead to more activities for these children and adolescents. But children or adolescents were not involved in the planning or decision-making of the activities. The studies in this thesis show that most important thing for adolescents’ mental health is the relation between adolescents and adults, foremost parents, and between adolescents and friends. In addition, gender and age, adolescents’ perspec¬tives and par-ticipation, and society’s support, including the implementation of the UN Convention on the Rights of the Child, have an impact on adolescents’ mental health, both for ado-lescents in general and for adolescents at risk of abuse and neglect. The results are viewed in relation to the bioecological model, to illustrate how all levels in society influence mental health among adolescents, on an individual and a population plane. The findings have implications for adults: to learn more about adolescents and puberty, and about the home situation for children and adolescents at risk of abuse and neglect; to listen to suggestions from children and adolescents; to include friends in support to adolescents at risk of abuse and neglect; and to include girls and boys in all matters concerning them.