This talk will discuss the implementation of LanguageKit and cover some of its current and potential uses. LanguageKit is used to implement Ètoilé's Pragmatic Smalltalk, which generates classes that are ABI-compatible with Objective-C, meaning that Objective-C and Smalltalk classes can subclass or extend each other, with no bridging overhead.  In common cases Smalltalk performance is similar to that of Objective-C.