Any professional activity worth its name will have developed criteria and concepts that help to guarantee the quality of its products (see Stevens, Schade, Chalk, and Slevin, 1993, p. 6, concerning health care professionals). Interestingly this stage does not seem to have been realised yet for systems professionals in the social domain. Not only early workers have been worried (Ackoff, 1981; Beer, 1985; Checkland, 1981), but also more recent ones (Checkland, 1992; De Zeeuw, 1995; Van der Zouwen, 1996).