Introduction International evidence suggests that youth who leave mainstream education early have poorer mental health and social outcomes than their peers. In the European Union, 11.1% of youth leave mainstream education before completing upper-secondary school. Early school leaving is associated with challenging home environments and parents’ socio-economic background, and is likely to result in further disadvantage by limiting the young person’s access to employment or further education and training. In Ireland, an alternative education (AE) programme, Youthreach, provides an opportunity for young people who have left school early to achieve second level qualifications and vocational training. However, the social, personal and educational challenges experienced by many of these young people highlight the need for effective strategies to build resilience and improve the mental health and wellbeing among AE students to ensure successful completion of their studies and prevent mental health problems. Computerised mental health programmes for preventing anxiety and depression have been shown to be effective and acceptable with young people. However, the delivery of such programmes universally and to more vulnerable groups of young people needs to be further studied. Furthermore, the high drop-out and low engagement rates attributed to computerised mental health interventions call for increased implementation research to understand reasons behind disengagement. Aims The overall aim of this thesis is to examine the feasibility of delivering computerised mental health programmes within the AE setting in order to improve student mental health and wellbeing and prevent mental health problems. The aim of Paper I is to review the literature on the effectiveness of computerised mental health promotion and prevention interventions with youth in order to identify evidence-based programmes and gaps in the existing knowledge base. Paper II explores the needs and preferences of AE students and staff in relation to the implementation of computerised mental health programmes, to guide the implementation and evaluation of these programmes in the AE setting. The aim of Paper III is to examine the effectiveness of SPARX-R computerised cognitive behavioural therapy (cCBT) programme for preventing depression and improving wellbeing among young people attending AE. Finally, Paper IV examines user views on the implementation of SPARX-R, particularly focusing on factors that may have influenced programme engagement and drop-out. Methods This study incorporates a systematic literature review (Paper I), a qualitative requirement analysis of the needs and preferences of AE students (age 15-20 years) and staff in relation to the delivery of computerised mental health programmes (Paper II), and a randomized controlled trial (RCT) with integrated implementation research to examine the effectiveness (Paper III) and implementation (Paper IV) of SPARX-R cCBT in alternative education. In Paper I, the effectiveness of online mental health promotion and prevention interventions with youth (12-25 years) is examined by means of a systematic literature review. Outcomes of interest included indicators of mental health (e.g. depression and anxiety) and social and emotional wellbeing (e.g. self-efficacy, self-esteem and coping skills). RCTs, quasi-experimental studies and experimental studies without a control group were included in the review. In Paper II, student and staff needs are assessed using the Requirements Development Approach (Van Velsen et al., 2013). First, an online staff survey (n = 16) was conducted to provide information on the Youthreach staff and students. Stakeholder requirements were further explored in four student workshops (n = 32) and staff discussions (n = 12). Paper III reports on a cluster RCT (n = 146) with an intervention (SPARX-R) and no-intervention control condition. Measurements were taken at baseline and post-intervention, including indicators of positive mental health (general mental wellbeing, coping and emotion regulation) and mental health problems (depression and anxiety). Participants that provided data at post-assessment (n = 66, 45.2%) were included in the outcome analysis. Implementation research was integrated in the trial and the findings are reported in Paper IV. The implementation research consists of a post-intervention implementation questionnaire (n = 28), process evaluation questionnaires and post-intervention open-ended responses (n = 12). Furthermore, the staff moderators completed a staff feedback questionnaire (n = 6) with three staff members also participating in interviews. Results In Paper I, the results show that computerised mental health promotion and prevention interventions are effective in improving mental health and wellbeing and reducing symptoms of anxiety and depression in youth. However, high dropout and low engagement rates were consistently reported in studies, indicating a need for increased implementation research to better understand the factors determining engagement. Furthermore, most studies were conducted with university student or secondary school student populations, with no studies focusing on more vulnerable groups of young people, who are at a greater risk for mental health problems. Paper II showed that AE student and staff have quite specific needs and preferences that need to be met in delivering computerised mental health programmes, arising from issues with low levels of literacy and concentration, and the vulnerability of the students. Thus, programmes need to be customisable, fun and interactive and not text-heavy, use a positive strengths-based approach and ensure confidentiality and optional attendance. Staff need to be able to monitor and support students and require structure and timetabling to ensure sustained delivery, while also allowing for flexibility in delivery taking into consideration the needs of individual students. In Paper III, a significant improvement in emotion regulation strategies was detected, with expressive suppression decreasing significantly in the SPARX-R group in comparison to the control (-2.97, 95% CI -5.48 to -0.46, p = 0.03). No significant changes were detected on other outcome measures. High levels of attrition and low levels of engagement were reported, with a dropout rate of 55% and only 30% (n = 9) of participants completing the entire programme. The findings from Paper IV indicate that the reasons for low engagement and high dropout as reported in the RCT, were related to the programme and the context of delivery. Technical issues, lengthiness and the lack of positive focus, as well inconsistencies in student attendance and interruptions in the curriculum were reported as the main reasons for disengagement. However, the findings also show that SPARX-R is easy to use for youth with low levels of literacy. Increased staff training and integrating the programme into face-to-face sessions may improve engagement rates and programme satisfaction. Conclusions This study adds to the existing literature by providing novel insight into the factors that need to be considered when developing and/or implementing computerised mental health programs with more vulnerable groups of young people. Few studies to date have examined, in such detail, user views on the implementation of computerised mental health interventions, or the use of such programmes with more vulnerable youth. The findings indicate a need for increased focus on developing computerised mental health promotion programmes that are based on building social and emotional skills. Young people attending AE, in spite of being at a higher risk for mental health problems, prefer universal programmes that are positive, and strengths-based rather than problem-based. Although further studies with larger samples are needed, the serious gaming approach used in SPARX-R shows potential as an easy to use and effective way of improving student wellbeing with populations with low levels of literacy. However, the findings also highlight the importance of contextual factors, such as staff training, integrating programmes into a dedicated mental health curriculum and complementing them with face-to-face interaction, in supporting effective delivery of computerised mental health programmes in the AE setting.