This volume constitutes the proceedings of the 11th International Workshop on Groupware (CRIWG 2005). The conference was held in Porto de Galinhas (Recife), Brazil. The previous ten CRIWG workshops were organized in Lisbon, Portugal (1995), Puerto Varas, Chile (1996), El Escorial, Spain (1997), Buzios, Brazil (1998), Cancun, Mexico (1999), Madeira, Portugal (2000), Darmstadt, Germany(2001), La Serena, Chile (2002), Autrans, France(2003), and San C- los, Costa Rica (2004). CRIWG workshops follow a simple recipe for success: good papers, a relatively small number of attendees, extensive time for lively and constructive discussions, and a high level of cooperation both within and between paper sessions. CRIWG 2005 continued this tradition. This 11th CRIWG exempli?ed the continuing interest in the groupware - searcharea.Groupwareresearchersfrom 16 di?erent countriessubmitted a total of67papers.Eachofthe67paperswasreviewedbyatleastthreemembersofan internationally renowned Program Committee, using a double-blind reviewing process. Based on the reviewers' recommendations 29 papers were ?nally - cepted: 16 long papers presenting mature work, and 13 short papers describing workinprogress.Theacceptedpapersweregroupedinto8themesthatrepresent current areas of interest in groupware research: groupware development, coll- orative applications, work?owmanagement, knowledge management, comput- supported collaborativelearning, groupdecision support systems, mobile coll- orativework, andworkmodeling inCSCW. In addition, wewerepleasedto have Gerry Stahl from Drexel University in Philadelphia, USA, a renowned specialist in CSCL, as keynote speaker.