'Barriers to entry' as an economic concept was defined by Joe Bain in his 1956 book Barriers to New Competition. Bain's analysis focused on the ways in which various industries functioned within the market: whether there were few or many firms in each industry, how labour-intensive/expensive they were, and whether or not there was collusion among existing firms to prevent the entry of new, competing ones. This is the first book to focus on the different methods that economic science has employed in order to detect and measure barriers to entry. A chronological analysis is presented, as well as an in-depth look at the competing Harvard and Chicago Schools' interpretations of this phenomenon.