Mental health promotion programs (MHP) seek to reduce sub-syndromal symptoms of mental distress and enhance positive mental health. This study evaluates the long-term effects of a mindfulness-based MHP program (‘Life Balance’) provided by health coaches in a multi-site field setting on mental distress, satisfaction with life and resilience. Using a controlled design, propensity score matching was used to select a control group for participants of the MHP. The total study sample (N = 3624) comprised 83% women, with a mean age of 50 years. Data was collected via mailings 1 year after study entry. Results suggest participants experience reduced emotional distress at 12-month follow-up, with a medium between-group effect size (d = 0.40) for those participants who showed clinically relevant symptoms of mental distress at study entry. The effects of the program were more pronounced in participants with higher initial distress scores. New cases of psychopathological symptoms were prevented in 1 of 16 participants. Satisfaction with life and resilience were enhanced significantly. Our data suggest ‘Life Balance’ shows long-term effectiveness and indicate it is possible to design MHP programs that serve as both primary and indicated prevention, and that these programs can be applied on a population basis.