Mental health concerns such as depression and anxiety are becoming increasing prevalent in an adolescent population. In New Zealand, public mental health services have long waitlists to access support from a clinician and private clinicians are often costly. This creates a barrier for many adolescents to receive support, particularly those who are experiencing subclinical concerns. There is also some evidence to suggest that many people do not benefit from traditional therapy approaches. Acceptance and Commitment Therapy (ACT) is an alternate to traditionally used treatment approaches such as Cognitive Behavioural Therapy and uses techniques such as values, acceptance and mindfulness to help improve wellbeing. Using ACT in a self-help format helps to reduce barriers for adolescents to access support. The overall purpose of this study was to address the question “Does the self-help book Get Out of Your Mind and Into Your Life for Teens improve wellbeing in adolescents?”. In particular, the research sought to find out i) if the book was effective in improving well-being in adolescents, ii) if there were any gender differences in outcomes and iii) understanding if adolescents found the book useful by evaluating if it was easy to work through and relevant to them. Participants were between the ages of 16 and 18 years (N=16, average age= 16.6), with nine females and six males. A total of 14 participants completed the intervention. The study was conducted using a multiple baseline design. Participants completed a battery of questionnaires which focused on wellbeing and ACT techniques at 4 time points (before the baseline period, after a two week wait before they began the intervention, on completion of the intervention and at a two month follow up), specific areas assessed by the questionnaires were depression, anxiety, strengths and difficulties, thought control, acceptance and mindfulness. During the intervention period, participants worked through the book and engaged in weekly meetings. Participants also filled out a number of questionnaires specific to wellbeing and ACT at four time points. When the group data as well as individual change scores were analysed, statistically significant improvements were found for depression, thought control and acceptance. There were no gender differences in response to the intervention. The majority of participants felt that the intervention was relevant and useful. They also reported that they were able to use some of the skills from the intervention in their everyday lives. These findings indicate that this intervention was effective for improving general wellbeing with adolescents who are experiencing sub-clinical levels of distress. Furthermore, it demonstrates that adolescents were able to learn ACT based techniques from the self-help book and that they found the book useful and relevant. In conclusion, this study has shown that ACT based self-help interventions may be used as an alternative and cost-effective method of offering support to adolescents. It also shows that adolescents will engage in this type of intervention and can use the techniques they learn in their everyday lives. This information will hopefully be of use to professionals who work with adolescents who are experiencing mental health concerns.