<p>This paper describes the process of developing and testing a family nursing scale called Family Care during Child’s Illness (FCCI). The scale is based on Maijala’s (2004) substantive interaction theory. The empirical focus is on the provision of interactive nursing care for families of children aged one to three who require acute hospital care primarily for somatic reasons. The scale is intended for the purpose of measuring caregivers’ assessments of care provision in families where the child is potentially in a very serious and precarious situation and where there is much uncertainty (Meiers and Tomlinson 2003, Gedaly-Duff et al 2005). Typically, the need for acute hospital care is due to an accident, the onset of diabetes, cancer or an infectious disease.</p>