This paper presents the results of a study to increase knowledge of the nature of post-implementation web IS, and issues inherent in ongoing web IS management. It employs a new socio-technical framework, Kling's STIN, to organize and analyze field data from four large U.S. manufacturing companies. The paper finds that post-implementation web IS are highly dynamic systems composed of multiple technical and non-technical components. The paper illustrates how web IS are socially embedded by showing how social components compromise an integral part of the technological system, and by providing examples of how social forces shape the technical components of the system. Using the STIN framework and the case study data, the paper outlines major groups of actors of dependencies which comprise the STIN. The paper argues that web IS are transitory, socially negotiated artifacts. It suggests a new view of web IS configurations as reflections of current organizational power arrangements.