This paper describes a design specification and analysis framework to support the OO design stage. Structural and behavioral specifications of objects are integrated and formalized. To achieve this task, an object-oriented design language that captures the structural and behavioral models was defined. An environment consisting of a graphical user interface (GUI) and a processor for the language was implemented. The GUI supports the generation of UMLbased designs. The major tasks of the processor are syntactic and semantic analyses, and code generation. Thus, designs can be evaluated and validated before implementation.