HiPEAC2009wasthe fourthedition ofthe HiPEACconferenceseries.This c- ferenceseriesislargelyassociatedwiththeFP7NetworkofExcellenceHiPEAC2. The ?rst three editions of the conference in Barcelona (2005), Ghent (2007) and G] oteborg (2008) attracted a lot of interest with more than 200 attendees at the last two editions and satellite events. It is a great privilege for us to welcome you to the fourth HiPEAC conference in the beautiful, touristic city of Paphos, Cyprus. The o?erings of this conference are rich and diverse. We o?er attendees a set of seven workshopson topics that are central to the HiPEAC network roadmap: multi-cores, simulation and performance evaluation, compiler optimizations, - sign reliability, recon?gurable computing, and interconnection networks. Ad- tionally, a tutorial on design reliability is o?ered. Theconferenceprogramwasasrichaslastyear's.Itfeaturedmanyimportant andtimelytopicssuchasmulti-coreprocessors, recon?gurablesystems, compiler optimization, power-awaretechniquesand more.The conferencealso o?ered two keynote speeches: Tilak Agerwala from IBM Research presenting the view from a major industry player, and Fran, cois Bodin from CAPS-Entreprise presenting the view of a start-up. There were several social activities during the conference o?ering ample - portunity for informal interaction. These included a reception, an excursion to various archeological sites and a banquet at a traditional tavern. Thisyearwereceived97papersubmissions, ofwhich14wereco-authoredbya Program Committee member. Papers were submitted from 20 di?erent nations (approximately 46% from Europe, 15% from Asia, 32% from North America, 4% from Africa and the Middle East, and 3% from South America), which is an indicator of the global visibility of the conference."