For the ?fth time in its history, in cooperation with Springer-Verlag, the European C- ference on Object-Oriented Programming (ECOOP) conference series is glad to offer the object-oriented research community the ECOOP 2001 Workshop Reader, a c- pendium of workshop reports, panel transcripts, and poster abstracts pertaining to the ECOOP 2001 conference, held in Budapest from 18 to 22 June, 2001. ECOOP 2001 hosted 19 high-quality workshops covering a large spectrum of - search topics. The workshops attracted 460 participants on the ?rst two days of the conference. Originally 22 workshops were...