Background: Computerized cognitive behavioral therapy (cCBT) has been shown to improve mental health and wellbeing in youth, however, high drop out and low engagement rates are reported in many studies. This study examined the factors that contribute to engagement and dropout with SPARX-R, cCBT program for preventing depression and improving wellbeing with a group of vulnerable 15-20 year olds attending alternative education (AE).Methods: Students who took part in a randomized controlled trial (RCT) of SPARX-R completed a post-intervention implementation questionnaire (n = 28) and provided verbal or written feedback (n = 12) on their experience of the program. Furthermore, process evaluation questionnaires completed after each level of SPARX-R examined the views of participating students, including those who dropped out of the study. Staff views were also explored through a post-intervention questionnaire and interviews.Results: The majority of the students considered SPARX-R easy to use and agreed that the program made sense to them. However, less than half of the participants reported that they liked the look of the program or considered it fun, and only a third reported that they would recommend SPARX-R to a friend. Those categorized as being at risk for depression, as assessed on the Short Moods and Feelings Questionnaire, rated the program higher in terms of its relevance and usefulness in comparison to those with no symptoms or clinical symptoms of depression. Technical issues, lengthiness and the lack of positive focus were the main reasons reported for negative reactions and disengagement with SPARX-R. Staff expressed a need for increased flexibility in delivery and complementing computerized programs with face-to-face activities to improve student engagement.Conclusions: Computerized delivery can offer multiple benefits to mental health promotion and prevention in educational settings. Further research is needed to examine how such programs can be incorporated into existing approaches and made more positive and adaptable to support universal delivery for more vulnerable young people.