TheprogramstartedwithafulldaytutorialontheCASL,followedby32 presentations,severalofthemontheCASLaswell,organizedinparallelsessions duringthefollowingtwodays. Theparallelsessionsweredevotedto:logicsand proofs,concurrentprocesses,institutionsandcategories,applicationsandcase studies,higher-orderandparameterizedspeci?cations,staticanalysis,software architectures,graphandtransformationrules. Themaintopicsoftheworkshopwere: –algebraicspeci?cation –otherapproachestoformalspeci?cation –speci?cationlanguagesandmethods –termrewritingandproofsystems –speci?cationdevelopmentsystems(concepts,tools,etc. ) Theprogramcommitteeinvitedsubmissionsoffullpapersforpossibleinclusion inthisvolume,onthebasisoftheabstractsandthepresentationsatWADT 2001. Allthesubmissionsweresubjecttocarefulrefereeing,andtheselectionof paperswasmadefollowingfurtherdiscussionbythefullprogramcommittee.