This is a thesis in marketing concerned with entrepreneurship in established firms and the discursive practices that take place within a perspective of strategic entrepreneurship. The study of discursive practices in this context assumes a concern with how different aspects of entrepreneurship are produced and consumed by people in text and talk. Strategic entrepreneurship can be seen as an organisational form of entrepreneurship. The latest contribution within strategic entrepreneurship tends to focus on opportunities and advantages in organisations as two processes that need to be considered and managed jointly. In this thesis, I have studied the discursive practices of how scholars position strategic entrepreneurship through an enhanced literature review and by means of a close analysis of assumptions made within strategic entrepreneurship, but also by studying two firms and their discursive practices of constructing opportunity and advantage positions. The results have then been analysed with reference to discourse theory and previous research within entrepreneurship based on European traditions that builds on the linguistic turn. By conducting an empirical study of two firms, I have studied discourses in use, and how they are produced by people. In so doing, two main findings emerge in the discussion of the empirical results: 1) Opportunity and advantage positions emerge in social interaction and are co-constructed. 2) Opportunity and advantage positions are constructed by the use of multiple discourses, on different levels of discourse and for different functions. The main purpose of the thesis is to enhance the understanding of entrepreneurship in established firms and the activities labelled as strategic entrepreneurship. In addressing the purpose, seven theoretical, methodological and empirical contributions to research emerge in areas of strategic entrepreneurship, entrepreneurship and the enterprising self.