To evaluate the construct validity and the inter-rater reliability of the Dutch Activity Measure for Post-Acute Care “6-clicks” Basic Mobility short form measuring the patient’s mobility in Dutch hospital care. First, the “6-clicks” was translated by using a forward-backward translation protocol. Next, 64 patients were assessed by the physiotherapist to determine the validity while being admitted to the Internal Medicine wards of a university medical center. Six hypotheses were tested regarding the construct “mobility” which showed that: Better “6-clicks” scores were related to less restrictive pre-admission living situations ( p = 0.011), less restrictive discharge locations ( p = 0.001), more independence in activities of daily living ( p = 0.001) and less physiotherapy visits ( p r= −0.408, p = 0.001), but not between the “6-clicks” and age ( r = −0.180, p = 0.528). To determine the inter-rater reliability, an additional 50 patients were assessed by pairs of physiotherapists who independently scored the ...