Abstract Objectives Parents of children with a chronic illness (CI) are at risk for psychosocial problems. The aim of this study was to refine an existing face-to-face intervention into an online psychosocial group intervention for parents by (1) exploring which themes are important, (2) determine what type of intervention parents would like and (3) assess parents’ practical preferences. Methods Parents of children with a CI (0–18 years) were invited to complete an online questionnaire. To acquire more in-depth information, focus groups and telephone interviews were conducted. Descriptive statistics were used. Results 272 parents (mean age = 43.1 years, 85% female) participated. Three focus groups (15 parents) and seven telephone interviews were conducted. Most important themes were: the CI of the child, family functioning, taking care of yourself, relationships with others and practical support. Parents preferred a group with parents of children in the same age category. At first, parents preferred face-to-face contact. After an explanation and demonstration of an online intervention, parents became more positive about online support, mostly because they could participate from home. Conclusions for Practice Parents have a need for psychosocial support focusing on different themes. Professionals should explain and demonstrate an online intervention to parents. Based on these results, Op Koers Online for parents was developed. An RCT to assess feasibility and effectiveness of the intervention is currently running.