Background: A demand-oriented approach is becoming increasingly important in care provision. The purpose of this study was to identify the primary needs of clients with Severe Behavioural Disorders and Severe Intellectual Disabilities. Materials and Methods: We used the theory of Social Production Function and Maslow's hierarchy of needs to operationalize different types of needs of clients with Severe Behavioural Disorders and Severe Intellectual Disabilities. A Q-methodological study enabled us to distinguish the needs of 23 clients. Results: Two needs prioritizations were found. Physical well-being ultimately weighs most heavily for all clients, but in one of the two groups affection and behavioural confirmation (i.e. social needs) were also found to be important. There were no significant differences in needs between clients whose main behavioural difficulty was aggression and clients whose main behavioural difficulty was self-harm. Conclusions: A demand-oriented policy for clients with Severe Behavioural Disorders and Severe Intellectual Disabilities should be targeted at groups with different needs prioritizations, rather than groups with different behavioural problems. That does not mean that the same needs of different clients can be met in exactly the same way. It takes creativity and a person-centred approach to find ways to enable clients to realize their social and physical needs.