As both business and technology environments change at a fast pace, software team flexibility in responding to requirement changes has become a critical software project success factor. However, little research has empirically examined software team flexibility in terms of its key dimensions, its determinants, and its impacts on software project performance. In this paper, we define software team flexibility in terms of its response extensiveness and response efficiency to system requirement change requests. Using survey data of 505 software development projects, we tested a research model and hypotheses regarding relationships among the dimensions of software team flexibility, team autonomy, team diversity, and project performance. The results revealed a negative relationship between the two dimensions of software project team flexibility. Team response efficiency positively affected both project process performance and software functionality, whereas team response extensiveness positively impacted only software functionality. While increased team autonomy helped enhance software team response efficiency, it reduced software team response extensiveness. In contrast, increased team diversity helped improve software team response extensiveness. The results suggest that, when it comes to issues related to software team flexibility, project managers must be aware of and effectively manage a complex set of tradeoffs among the various variables.