Background The childcare environment offers a wide array of developmental opportunities for children. Providing children with a feeling of security to explore this environment is one of the most fundamental goals of childcare. Objective In the current study the effectiveness of Video-feedback Intervention to promote Positive Parenting-Child Care (VIPP-CC) was tested on children's wellbeing in home-based childcare in a randomized controlled trial. Methods Forty-seven children and their caregivers were randomly assigned to the intervention group or control group. Children's wellbeing, caregiver sensitivity, and global childcare quality were observed during a pretest and a posttest. Results We did not find an overall intervention effect on child wellbeing, but a significant interaction effect with months spent with a trusted caregiver was present. Children who were less familiar with the caregiver showed an increase in wellbeing scores in both the intervention and control group, but for the group of children who were more familiar with the caregiver, wellbeing increased only in the intervention group. Conclusions Although there was no overall effect of the VIPP-CC on children's wellbeing, the VIPP-CC seems effective in children who have been cared for by the same trusted caregiver for a longer period of time. (author abstract)