Recently, aspect-oriented approaches have resulted in a tremendous impact on the processing of broadly scoped properties during the development of software systems. However, the weaving mechanism of these crosscutting concerns cannot be easily represented with the extant unified modeling language (UML) notation at the early stage of software development life cycle. As an attempt toward the investigation of how the crosscutting behavior takes place, we proposed, in this work, an aspect-enhanced goal-driven approach to modeling the aspectual behavior in UML state transition diagrams and sequence diagrams with the proposed interaction operators based on the aspectual weaving semantics. By introducing the proposed interaction operations in the UML combined fragment, UML sequence diagrams can be further enhanced to support the modeling of the interactions between aspectual and base behavior in the analysis and design stage of software development. To further exemplify our points, the meeting scheduler system is chosen as a vehicle to illustrate the proposed approach. (c) 2010 Wiley Periodicals, Inc.