This is a parallel 3-group, multicenter, prospective, randomized, single-blind (evaluator) controlled pilot trial, with a 38- week follow-up. Patients diagnosed with bipolar disorder (BD) according to DSM -5 criteria for mild depression or subsyndromal depressive symptoms are assigned to one of the following 3 treatment groups: 1) psychopharmacological treatment plus Mindfulness Based Cognitive Therapy (MBCT); 2) psychopharmacological treatment plus structured group psychoeducation; 3) treatment as usual (TAU), including standard psychiatric care with standard pharmacologic treatment.