A Dutch version of the ‘Measure of Processes of Care for Service Providers’ (MPOC-SP) was developed to determine the extent to which professionals apply the principles of family-centred care in the rehabilitation of children with physical disabilities. However, no data were available on the reliability and construct validity of this instrument when it comes to supporting people with profound intellectual and multiple disabilities (PIMD). This study aimed to validate an adapted version of the Dutch MPOC-SP for assessing the family-centred behaviours of professionals who support this group (MPOC-SP-PIMD). A total of 105 professionals took part in the study. A Mokken scale analysis was conducted to determine whether the instrument satisfied the assumptions of both monotone homogeneity and double monotonicity. Loevinger's scalability coefficient (H) was used for the scalability of the entire scale and of each item separately. Rho was calculated as a measure of the internal consistency of the scales. The analyses resulted in two scales: a nine-item scale interpreted as ‘Showing Interpersonal Sensitivity’, with H = .39 and rho = .76, and a seven-item scale interpreted as ‘Treating People Respectfully’, with H = .49 and rho = .78. A validated version of the MPOC-SP-PIMD, suitable for supporting people with PIMD, consists of a subset of two scales from the original Dutch MPOC-SP. This instrument can be used to compare the family-centredness of professionals with parent's expectations and views. This information can be used in practice to match the support to the needs of the parents and family of the child with PIMD.