Objective Professionals in dementia-care ought to be able to work within a Bio-Psycho-Social model. The objectives were to examine whether dementia-care is delivered in a Bio-Psycho-Social way, to explore the influencing factors and to evaluate the factorial validity of the ‘Bio-Psycho-Social-Dementia-Care scale’. Design and setting 413 healthcare-professionals completed the ‘Bio-Psycho-Social-Dementia-Care scale’. Differences between groups (settings, professions, years of experience) were calculated with a student’s t-test and one-way ANOVA. The facture structure of the scale was evaluated using a confirmatory factor analysis. Results The factor-analysis confirmed the 5 subscale-structure (1) networking, (2) using the client’s expertise, (3) assessment and reporting, (4) professional knowledge and skills and (5) using the environment. (No significant differences were found between professionals in residential care and community care for the subscales ‘networking’ and ‘using the client’s expertise’. Professionals in residential care score higher than community care for ‘assessment and reporting’ (p<0,05) and ‘professional knowledge and skills’ (p<0,01) but lower for ‘using the environment’ (p<0,001). The juniors score higher for ‘professional knowledge’ compared to seniors (p<0,01) and the seniors score better for ‘professional experience’ (p<0,01). The Cure and Care disciplines and the Therapy disciplines had higher values in ‘assessment and reporting’ compared to the Social Support disciplines (p<0,001 and p<0.001). The Therapy disciplines scored higher in ‘using professional knowledge and skills’ compared to the Social Support group (p 0.021) and the Cure and Care disciplines (p<0,001). The Social Support disciplines scored higher in ‘using the environment’ compared to the Therapy disciplines (p<0.001) and the Cure and care disciplines (p<0.001). Conclusion The Bio-Psycho-Social-Dementia-scale is a valid tool and offers opportunities not only to rate, but also to improve Bio-Psycho-Social functioning in dementia-care: increase interdisciplinary collaboration, facilitate assessment, combine the strengths of the different professions and install a heterogeneous team with regard to age and experience.