This volume contains the proceedings of the 17th IFIP TC6/WG6. 1 Inter- tional Conference on Testing of Communicating Systems (TestCom 2005). The conference was held at Concordia University, Montr' eal, Canada, from May 31 to June 2, 2005. TestCom 2005 was organized by Concordia University and was sponsored by IFIP. Following the trends initiated at the 16th edition of the conference held in Oxford, UK, the ?rst call for papers issued in summer 2004 called for contri- tions from the general software testing community. The goal of the conference thisyearwas tocontinue the broadeningofthesubject. The themeoftheconf- ence this year is "Meeting Software Testing. " In response to the call for papers, we received 62 abstracts. Out of these abstracts, 53 turned into paper subm- sions. Each of these submissions was evaluated by at least 3 reviewers from the Technical Programme Committee, with the help of additional co-reviewers when needed. The Programme Committee meeting was held online from January 18 to January 30, 2005. Out of the 53 submitted papers, the Programme C- mittee selected 24 papers covering the traditional topics of TestCom, such as EFSM/FSM model-based testing, and also papers on general software testing re?ecting the new trends in the conference. We are very grateful to the keynote speaker, Prof. Tom Maibaum, from McMaster University, Hamilton, Canada. Prof. Maibaum addressed TestCom 2005 on this year's theme. He kindly provided an extended abstract, which is also included in this volume.