In most markets, firms need to be aware of their rivals, and even potential rivals, when making decisions. In other words, they must act strategically. We will analyse strategic decision making on prices, product specifications, and investments which will be relevant to anyone with an interest in corporate strategy. But our concern will extend beyond the firms concerned, to the implications for welfare more generally. The module thus begins with a discussion of competition policy in the UK, the European Union and the USA. Throughout the module, theoretical and empirical analysis will be linked to contemporary and classic cases.