Aims: Young people often seek help from their peers for mental health problems. However, little is known about young people's experiences of helping a peer with a mental health problem. The aim of this study was to systematically review the literature on young people's help-giving actions, highlight any gaps in the research and examine the evidence for interventions designed to increase and improve help-giving.The secondary aim was to compare findings between help-giving in face-to-face and online settings.Methods: Embase, SCOPUS, PsycINFO and MEDLINE electronic databases were searched for English studies published from 2003 onwards. Studies focusing on the help-giving actions of young people (aged 12-25 years) towards a peer with a mental health problem were included. Risk of bias was assessed using the Joanna Briggs Institute quality appraisal tools. Data were synthesized using thematic and narrative analysis.Results: Twenty-one studies (3440 participants) were included. The most frequently reported help-giving themes were encouraging professional and adult support and providing emotional support. Although limited studies reported on online help-giving, online settings allowed for immediate help to be provided despite time or location.Both positive and negative outcomes for helping were identified. Improvements in the quality of help-giving were found after training; however, help-giving for mental health crises was poor.Conclusions: Further research regarding the young people's help-giving actions to peers online is required. Training programs need to consider how to further improve the quality of help-giving among young people and to increase the trainees' confidence in helping, particularly in a mental health crisis.