Measuring family caregivers experiences of collaboration with nurses is important in the context of health care reforms that advocate an increased role of families in care. The Family Collaboration Scale (FCS) measures collaboration between nurses and family caregivers, however, the scale has a broad scope. Thus, the aim of this study was to construct a measure that is focused on collaboration only. After revision, a 25-item version of the FCS was sent to 777 family caregivers of hospitalized patients (amp;gt;= 70 years). Psychometric evaluation was employed by the Non-Parametric Item Response Theory to evaluate how items of the revised FCS behave. In total, 302 (39%) family caregivers were found eligible, mean (SD) age 65 (13) and 71% female. A 20-item FCS is proposed showing good psychometric properties. This study contributes to the limited knowledge of measuring collaboration between family caregivers and nurses. (C) 2019 Elsevier Inc. All rights reserved.