Participation in a pediatric, complex randomized controlled trial (RCT) might add to the family burden when a child is diagnosed with a severe disease. This study explored parents’ and children’s motivation to and experiences of participation in a research study shortly after the child had been diagnosed with type 1 diabetes. Sixteen parents and nine children were interviewed by an independent researcher about their inducement, the decision-making process within the family which led to their participation, and their experience of having done so. The result showed that the parents wanted to contribute to improve treatment for children with diabetes in general but also specifically for their own child. Older children were more involved in the decision making than the younger children. Study information needs to be communicated clearly and effectively since decision-making based on information of a clinical trial directly after the child’s diabetes onset proved difficult.