Tailoring is an area of research in CSCW that allows interlacing design and use in a radical new way. Tailoring is closely related to end-user programming (e.g. spreadsheet development)and a general term to encompass both endeavours is End-User Development. This workshop address tailorability in context of evolving existing systems and applications to the needs of cooperative work practices and organisations. It includes also the cooperative activates of tailoring itself; i.e. collaboration between end users to accomplish tailoring and indirect collaboration between developers and end users to simplify the understanding of tailorable systems. The goal of the workshop is to compare and relate existing research on tailoring and enduser development in the CSCW community, to explore the challenges and future potentials of these technologies, and to identify further directions for research on end-user development in cooperative settings. The workshop is organised in co-operation with the European network of excellence on End-User development. (http://giove.cnuce.cnr.it/eud-net.htm