Childhood obesity is associated with severe physical and psychological health problems. Interventions are often directed at the whole family, but the literature provides no clear indication of the characteristics of an effective family-based intervention. The objective of the present paper is to study whether and how an analytical framework focusing on communicative authenticity can be used to observe and elaborate upon aspects of adherence in relation to health behavior change in a concrete family-based intervention. We do this by focusing on the families' experiences with a Shared-care health education intervention and thus explore the association between families' self-reported experience and their adherence to the intervention. The dataset consists of 21 in-depth semi-structured family interviews. The study shows that the Shared-care model has potential, but that this potential is rarely fulfilled in the intervention form under study. The sharing of care adds potential for several kinds of communicative authenticity because families are met by both the medical knowledge authority at the hospital and the local nurses in their municipality. It is, however, a significant finding that the families rarely benefit from this potential authenticity. Using theories of authenticity in this context adds theoretical and analytical potential and manages to incorporate elements of participation in tasks and practices of value, a sense of who we are and what we know, negotiation of meaning, emphatic caring, consistency between values and actions, and horizons of significance. The article brings new perspectives on how family-based interventions could be tailored to communicatively suit individual families.