ive semantics for aspect-oriented abstractions can be defined by language designers using extensible aspect compiler frameworks. However, application developers are prevented from tailoring the language semantics in an application-specific manner. To address this problem, we propose an architecture for aspect-oriented languages with an explicit meta-interface to language semantics. We demonstrate the benefits of such an architecture by presenting several scenarios in which aspect-oriented programs use the meta-interface of the language to tailor its semantics to a particular application execution context. Categories and Subject Descriptors D.3.3 [Software Engineering]: Language Constructs and Features—Classes and Objects, Frameworks; D.2.11 [Software Architectures]: Languages General Terms Design, Languages Keywords Aspect-Oriented Programming, Meta-Object Protocols, Open Implementation, Debugging, Aspect Interactions