This thesis aims at two different goals. First, a uniform presentation of the major relevant research results on EAOP-based expressive aspects. We motivate that these instantiations enable aspects to be defined more concisely and provide better support for formal reasoning over AO programs than standard atomic approaches and other proposed non-atomic approaches. Concretely, four groups of results are presented in order to substantiate these claims: 1. The EAOP model, which features pointcuts defined over the execution history of an underly- ing base program. We present a taxonomy of the major language design issues pertaining to non-atomic aspect languages, such as pointcut expressiveness (e.g., finite-state based, turing- complete) and aspect composition mechanisms (e.g., precedence specifications vs. turing- complete composition programs). 2. Support for the formal definition of aspect-oriented programming based on different seman- tic paradigms (among others, operational semantics and denotation semantics). Furthermore, we have investigated the static analysis of interactions among aspects as well as applicability conditions for aspects. The corresponding foundational work on AOP has also permitted to investigate different weaver definitions that generalize on those used in other approaches. 3. Several instantiations of the EAOP model for aspects concerning sequential program execu- tions, in particular, for component-based and system-level programming. The former has re- sulted in formally-defined notions of aspects for the modification of component protocols, while the latter has shown, in particular that expressive aspects can be implemented in a performance- critical domain with negligible to reasonable overhead. 4. Two instantiations of the EAOP model to distributed and concurrent programming that signifi- cantly increase the abstraction level of aspect definitions by means of domain-specific abstrac- tions.