This volume, the sixth in the Transactions on Aspect-Oriented Software Development series, focuses on the theme of aspects and model-driven engineering. The seven papers included in this issue give an in-depth coverage of the following topics: methods and techniques supporting separation, composition, and evolution of aspects identified in different development phases; simulation of runtime weaving of aspects using aspect-oriented models; techniques for verifying and validating aspect-oriented models; AOM case studies that provide significant insights into how aspect-oriented modeling techniques can be applied across the development life-cycle; tool support for use of integrated AOSD and MDE techniques; and language support for aspect-oriented modeling.