Humanity grows from making mistakes. However, there is a group of people, and their cost of mistakes might be higher than the average. They are therefore protected by others, and their opportunity to explore the world is deprived. This protective behavior could be unnecessary or excessive, which is defined as overprotection. To detect the overprotection issue in the field of pediatric cardiology, the researcher, together with Erasmus MC- Sophia Children's Hospital, set up a collaborative program. The ultimate goal of the program was to design a smart product-service system which can prevent overprotective behavior in children with congenital heart disease. The present thesis is the initial step of the collaborative program— investigation of overprotection in pediatric cardiology. It addresses the concept of overprotection (OP) and vulnerable child syndrome (VCS), studies on the health-related life of children with congenital heart disease (CCHD), and their parents (PCCHD), then proposes a reformulated design goal and three tangible design missions as the final result. In the literature review, theoretical knowledge of overprotection and vulnerable child syndrome is elaborated. Three factors are especially highlighted, respectively risk factor, challenge, and indicator. The risk factor indicates the event that may trigger overprotection development; challenge means the parental barrier of performing proper protection; indicator expresses the theoretical assessment of overprotection. These factors are further brought to the empirical study to see how they influence life of CCHD and PCCHD. Empirical insights are captured during the empirical study. A total number of eight interviews were conducted, and the researcher also attended a sharing event in which five CCHD gave speeches on their grown-up experience. Collecting the medical history, interaction with people around, and narratives or opinions about overprotection was the main purpose of the empirical study. Factors derived from the literature were continuously reflected and compared with the empirical data. Theoretical knowledge and empirical insights were further integrated and synthesized. Based on the empirical narratives, the applicability of the theoretical overprotection indicators in pediatric cardiology is evaluated. Two indicators are found to have the highest significance and thus are suggested as the prioritized behavior that needs to be prevented. In addition, extreme quotes and narratives are selected and formulated in a positive case and a negative case. The positive case indicates good patient-parent relation without overprotection reported, while the negative case means tension in patient-parent relation with overprotection reported. Each case contains a patient persona, a parent persona, a health journey map, and an interactive map. Besides discerning the existing factors, four beneficial triggers are generated and highlighted as the main determinants which contribute to the difference between the positive case and the negative case. The insights provide a hint for potential design directions— prevent risk factors, support users to overcome the challenges, and guide users toward the beneficial trigger. Based on the design directions, a reformulated design goal and three corresponding design briefs were proposed as the final result of the thesis. The design goal was framed as “Design a product-service system which facilitates rational discussions within children with congenital heart disease, their parents and medical experts, in order to achieve a consensus upon diagnosis-specific and personalized boundaries between proper-protection and overprotection.” The three design briefs are further written as three dependent design assignments that provide guidelines and suggestions to the following designers.