In Pharo 5.0 I see deprecated classes stripped of all methods and variables defined in a package like... Object subclass: #NBExternalStructure instanceVariableNames: '' classVariableNames: '' package: 'Deprecated50' It was was useful having these remain to facilitate loading Pharo 4.0's TalkFFI for a first look at porting it to Pharo 5.0. Somewhat expectedly, the class initialization fails with... MessageNotUnderstood: CXIdxDeclInfoStruct class>>rebuildFieldAccessors (since that method used to be in NBExternalStructure due to "NBExternalStructure subclass: #CXIdxDeclInfoStruct) But it would be nicer to get a Deprecated message rather than a MNU, initially something simple like this... Deprecated subclass: #NBExternalStructure Deprecated class >> doesNotUnderstand: DeprecatedError signal. but maybe later something like... Deprecated class >> doesNotUnderstand: Transcript crShow: self deprecationNotes. DeprecatedError signal. NBExternalStructure class >> deprecationNotes ^ 'Blah-d-blah. Use UFFIXxxxxx instead'. cheers -ben