Abstra t. Web servi es provide a suitable level of abstra tion and en ap-

sulation for the development of appli ations out of reusable and distributed

omponents. However, in order to in rease the appli ability of servi es as

well as to ne tune their exe ution in parti ular situations, ontext-adaptive

solutions are in reasingly required. In this hapter we des ribe a generi

knowledge-based framework for supporting the adaptation of Web servi es

and Web servi e-based appli ations to ontext. The framework builds upon

resear h in semanti Web servi es and Knowledge Engineering to support

apturing ontextual information in a way that is dire tly amenable to au-

tomated reasoning in order to support the re ognition of relevant ontextual

information that is then used for sele ting the most appropriate servi e or set

of servi es to be exe uted.