In this volume are the proceedings of the fourth European conference on - netic Programming (EuroGP 2001) which took place at Lake Como in Italy on April, 18{20 2001. EuroGP has become r mly established as the premier - ropean event devoted to Genetic Programming. EuroGP began life in 1998 as an international workshop and was held in Paris (14{15 April, LNCS 1391). - ter that it was held in Got ] eborg, Sweden (26{27 May 1999, LNCS 1598). Its r st appearance as a conference was last year in Edinburgh in Scotland (15{ 16 April, LNCS 1802). Each year EuroGP has been co-located with a series of specialist workshops (LNCS 1468, 1596, 1803). This year was no exception and EvoWorkshops 2001 were also held at Lake Como (18-19 April, LNCS 2037). Genetic Programming (GP) refers to a branch of Evolutionary Compu- tion in which computer programs are automatically generated over a period of time using a process that mimics Darwinian evolution. The 30 papers in these proceedings more than amply demonstrate the wide and varied applicability of GP. There are papers that apply GP to robotics, artic ial retina, character recognition, nancialprediction, digitall terandelectronic circuitdesign, image processing, data fusion, and biosequencing. In addition there are many papers that address foundational and theoretical issues. Arigorousdouble-blindrefereeing systemwasappliedtothe42submitted- pers. This resulted in 17 plenary talks(40% of those submitted) and 13 research posters.