Bipolar disorders are severe chronic disorders, marked by recurrent episodes of depression and (hypo)mania. The disorder usually emerges in early adulthood and tends to have a highly unpredictable course. Prevention of these episodes is essential, as they are associated with marked impairment in social and occupational functioning. The investigators propose to conduct a randomized, multi-center, observer-blind, parallel group controlled trial with an 78 week (18 month) intervention phase to test the hypothesis that continuous ambulatory real-time monitoring of early warning signs for new depressive or (hypo)manic episodes by smartphone based, innovative technology (e.g. GPS, acceleration sensor), including individual threshold- based early intervention for these early warning signs, will prolong time to a new mood episode and reduce hospitalizations (intervention group). In the control group ambulatory monitoring of early warning signs for emerging depressive or (hypo)manic episodes will occur in an identical manner, but the results will not be transmitted to the treating psychiatrist. All patients in this trial, irrespective of their group assignment, will receive guideline-based, state-of-the-art maintenance treatment.