Group model-building is increasingly used to support strategic decisio
n-making in organizations. However, little is known about its effectiv
eness, apart from anecdotal evidence and statements by consultants tha
t it works. This article reports on an assessment study of six group m
odel-building projects. Since few tested theories are available, case
studies and a qualitative research approach were used to shed more lig
ht on the effectiveness of group model-building projects in real organ
izations working on real strategic problems. The results show that a n
umber of hypotheses known from experience or textbook theory were 'con
firmed', while others were only partially confirmed or should be rejec
ted on the basis of the six cases investigated. (C) 1997 by John Wiley
& Sons, Ltd.