Table 1 Baseline characteristics
| Â | Intervention condition | Control condition | Total | Difference |
|---|---|---|---|---|
n =634 | n =707 | N =1341 | I-C | |
| Â | M(SD) | M(SD) | M(SD) | p |
 Gender (%) |  |  |  | .601 |
 Girls | 47.5 | 47.1 | 47.3 |  |
 Boys | 52.5 | 52.9 | 52.7 |  |
 Age | 14.0 (0.5) | 13.9 (0.6) | 13.9 (0.6) | .045 |
 Ethnicity (%) |  |  |  | .002 |
 Dutch | 79.0 | 86.8 | 83.1 |  |
 Other ethnicity | 21.0 | 13.2 | 16.9 |  |
 School level (%) |  |  |  | .015 |
 PVSE (Low) | 11.4 | 3.1 | 7.0 |  |
 HGSE (Middle) | 48.4 | 53.6 | 51.2 |  |
 PUE (High) | 40.2 | 43.3 | 41.8 |  |
Primary outcome | Â | Â | Â | Â |
 Depressive symptoms | 7.4 (5.6) | 7.7 (5.8) | 7.6 (5.7) | .430 |
Secondary outcomes | Â | Â | Â | Â |
 Anxiety | 6.6 (5.6) | 6.9 (5.6) | 6.8 (5.6) | .761 |
 Hopelessness | 3.5 (2.8) | 3.6 (2.8) | 3.5 (2.8) | .666 |
 Happiness | 7.9 (1.4) | 7.8 (1.3) | 7.8 (1.4) | .598 |
 Life satisfaction | 30.6 (7.2) | 30.4 (6.8) | 30.5 (7.0) | .675 |
 Optimism | 15.2 (4.2) | 15.4 (4.0) | 15.3 (4.1) | .008 |
 Active coping | 30.0 (7.2) | 29.2 (6.9) | 29.6 (7.1) | .570 |
 Cognitive coping | 27.6 (7.0) | 27.0 (6.7) | 27.3 (6.8) | .423 |
 Distraction coping | 17.8 (4.6) | 17.5 (4.9) | 17.7 (4.7) | .621 |
 Avoidance coping | 25.5 (5.7) | 25.3 (5.6) | 25.4 (5.7) | .544 |
 Seeking support coping | 18.7 (6.6) | 18.3 (6.2) | 18.5 (6.4) | .688 |
 Academic self-efficacy | 24.6 (5.3) | 24.5 (5.2) | 24.5 (5.3) | .776 |
 Social self-efficacy | 26.6 (4.3) | 26.1 (4.3) | 26.4 (4.3) | .299 |
 Emotional self-efficacy | 24.3 (5.2) | 23.9 (5.1) | 24.1 (5.2) | .316 |
Ancillary outcomes | Â | Â | Â | Â |
 School grades | 7.0 (1.1) | 7.0 (1.1) | 7.0 (1.1) | .638 |
 Classroom atmosphere | 4.0 (0.7) | 3.9 (0.7) | 4.0 (0.7) | .071 |
 Alcohol use past 4-weeks % | 21.0 | 21.2 | 21.1 | .975 |
 Current smoking % | 5.4 | 6.1 | 5.8 | .433 |
 Truancy % | 4.4 | 4.4 | 4.4 | .889 |