Abstract Background Many children experience parental separation and divorce. This experience is likely to negatively affect their wellbeing, conduct, psychological adjustment and social relations. Prevention of these problems thus has major priority but effective intervention programmes are still rare. This study therefore aimed to assess the effects of a 12-session preventive group intervention “Dappere Dinos™” for 6 to 8 year old children. Methods We performed a quasi-experimental study (registered as NTR 6788) on 105 children participating in the intervention group, 37 children with separated parents not participating (’divorce controls’) and 138 children from intact families (’intact controls’). Outcomes regarded children’s positive functioning (Parent Evaluation Form; Pedro-Carroll & Cowen, 1989), emotional and behavioral problems (Strengths and Difficulties Questionnaire; Goodman, 1997), and wellbeing (Cantril ladder, Cantril, 1965). Results Analyses showed that children’s positive functioning after participating in Dappere Dino’s increased according to mothers (MΔpre-post(SD) = 0.26 (0.32); p < .001). Also, children’s overall emotional and behavioral problems decreased after participation (MΔpre-post_mother(SD) = -2.02 (4.55); p < .01; MΔpre-post_trainer(SD) = -1.07 (4.34); p < .05; MΔpre-post_teacher(SD) = -1.64 (3.54); p < .01). Children’s wellbeing increased after participation (MΔpre-post_mother(SD) = 0.77 (1.02); p < .001; MΔpre-post_trainer(SD) = 0.69 (0.94); p < .001), or stayed the same (MΔpre-post_teacher(SD) = 0.19 (1.03); p = n.s.). No such changes were found in the two comparison groups. Conclusions After parental divorce, a 12-session preventive group intervention Dappere Dino’s™ for 6- to 8-year-olds can be efficacious in promoting children’s emotional well-being and positive functioning, and reducing their emotional and behavioral problems. Key messages Given the high ...