Several projects of the North German Association for Rehabilitation Research had focused on needs assessment in the field of medical rehabilitation to be provided by statutory pension funds. Their results prompted a more differentiated understanding of the concepts of rehabilitation-neediness, -ability and -prognosis and lead to the development of the "Lübecker algorithm". It is based on (a) assessing the present health disorder and its consequences in terms of activity limitations and participation restrictions, (b) defining rehabilitation goals, and (c) selecting a rehabilitative intervention. The three components form the corners of a triangle. Its connecting sides can be described in terms of norms and expectations (disorder-goals), theoretical considerations (disorder-intervention), and empirical evidence from systematic research (intervention-goals). Needs assessment can thus be--partly--objectified, and "need" can be safely distinguished from related concepts such as "burden of illness", "wish", "demand", "supply", and "provision".