Youth mental health as well as health equity are well-discussed topics within the public debate and within public health. Swedish young people who are being marginalized, for instance in relation to race, gender, class, ability, gender identity or sexual identity, are experiencing more mental ill health than other young people. Despite this knowledge, youth mental health programs do not seem to consider aspects of health inequities in the planning, conducting, or evaluation of interventions. The overall aim of this thesis was to explore understandings, meanings, and practices of equity in relation to everyday challenges, youth mental health, and public youth mental health promotion in Sweden. The thesis is a compilation of four qualitative studies. The first two are focus group studies with young people, the third is a critical discourse analysis of regional action plans for mental health, and the fourth a participatory action research study with practitioners working with young people. For the purpose of this thesis, the findings from each study were analyzed based on the overall aim of the thesis and synthesized. From the synthetization of the findings of the four studies, the different perspectives of young people, practitioners, and policy provided varied understandings, meanings, and practices of equity. The understandings of equity are represented by Equity as an ideal. The meanings of equity are represented by Equity as tangible inequities. The practices of equity are represented by Equity as (in) action. For inequities to become equity and for equity to become more than an ideal, actions on systemic injustices are needed. Action must come from participation by those marginalized by the unjust system and those hit hardest by youth mental health inequities, in order to lead to meaningful and sustainable change. Youth participation should not only entail practitioners inviting young people to participate, but also practitioners and policy supporting youth selforganization for mental health justice.