Abstract: Described herein are methods and systems for capturing functional and non-functional requirements of a software system. Both functional and non-functional requirements are captured in a framework that is easy for end users to use for participating directly at various levels of a requirements capture process. Functional aspects are desirably captured in terms of workflow notations to form a task flow model of the system, which in turn provides a desirable framework for eliciting and appropriately capturing the non-functional requirements. The task flow model updated with functional and non-functional requirements can be comprehensive and accurate enough to be used to generate test cases, to simulate usability and to generate conventional text based use cases. The requirements captured can be verified for quality of domain context to encourage re-use of domain terms.