There is an abundance of information in the literature on patient experiences with Internet support groups (ISGs). However, studies exploring these experiences in a rare disease population are scarce, even though these families are often at a disadvantage for resources, reliable information, and support. The aim of the current study was to explore the experiences with ISGs for parents of children with Cornelia de Lange syndrome (CdLS), a rare genetic diagnosis, in order to better understand the impact on emotional support and their child's medical care. Focus groups were conducted to inform the design of a large-scale internet survey. The survey asked parents closed- and open-ended questions regarding experiences with ISGs, with a focus on the psychosocial, medical, and logistical aspects. The survey found that 141/170 (82.6%) respondents have visited an Internet-based support group to find support or information about their child's CdLS diagnosis. The majority of respondents (71.7%) reported that ISGs have been helpful in finding emotional support, with the most common areas impacted as a result of ISG participation being behavior toward their children and family dynamic. Regarding medical care, most respondents (63.9%) reported that ISGs have been helpful in finding medical information and support, with the most commonly impacted areas of their child's care including day-to-day management, diet, therapy interventions, and healthcare providers. These findings provide a greater understanding of the role of Internet networking in healthcare and may inform future approaches to medical care and psychosocial support for rare, complex genetic diagnoses. © 2016 Wiley Periodicals, Inc.