Object-Process CASE Tool (OPCAT), which supports system development using Object-Process Methodology, meets the challenges of next generation CASE tools by providing a complete integrated software and system development environment. The main reasons for which CASE tools have spread at a lower pace than expected are their limited support of a particular method, high cost, lack of measurable returns, and unrealistic user expectations. Although many CASE tools implement familiar methods, their consistency checking and simulation capabilities are limited, if not inexistent, and the syntax and semantics of their graphic notations may not be clear to novice users. Based on two human cognition principles, OPCAT enables balanced modeling of the structural and behavioral aspects of systems in a single view through a bimodal visual-lingual representation. Due to this intuitive dual notation, the resulting model is comprehensible to both domain experts and system architects engaged in the development process. Due to OPM formality, OPCAT also provides a solid basis for implementation generation and an advanced simulation tool, which animates system behavior. This paper presents OPCAT and demonstrates its unique features through a small case study of a travel management information system.