Goals are a logical mechanism for identifying, organizing and justifying software requirements. Strategies are needed for the initial identification and construction of goals. In this paper we discuss goals from the perspective of two themes: goal analysis and goal evolution. We begin with an overview of the goal-based method we have developed and summarize our experiences in applying our method to a relatively large example. We illustrate some of the issues that practitioners face when using a goal-based approach to specify the requirements for a system and close the paper with a discussion of needed future research on goal-based requirements analysis and evolution. Keywords: goal identification, goal elaboration, goal refinement, scenario analysis, requirements engineering, requirements methods