Online mental healthcare resources have proliferated at a greater pace than evidence for their effectiveness. They may nevertheless be an attractive alternative for contemporary veterans and serving personnel who are reluctant to engage in traditional face to face treatment. This has created an urgent need to evaluate the effectiveness of online mental health care for the military community. This paper reports on the twostage evaluation of the Wellbeing Toolbox, a self-guided website for ex-serving members and their families. Stage 1 evaluated the reach and acceptability of the website. Results from user experience interviews and a survey of 291 open access users indicated that the site reached a relevant audience and was accessible and acceptable for the ex-service community. Stage 2 investigated the effectiveness of the Wellbeing Toolbox in achieving wellbeing goals ( the primary outcome) and other mental health outcomes ( secondary outcomes). All 30 participants in the effectiveness trial achieved at least some of their individual wellbeing goals, with most success in "getting active", "building support" and "keeping calm" goals. There was no corresponding improvement in overall mental health status. The value and role of self-guided online help is discussed.