There has been a growing academic interest in applying legitimacy as a theoreticallens to investigate, analyze, and theorize the occurrence of various phenomena in the business managerial domain. Most studies have investigated the legitimationof newness in different aspects, such as new ventures and new products in variousinstitutional settings. However, studies have failed to sufficiently investigate coemergenceand legitimation of newness and how new products are legitimized indifferent uncertain environments.The study explores the legitimation of newness in gambling and life sciencescontexts. The reason for selecting these contexts is that they are highly regulated,as the services and products offered by firms in this sector pose different risks tothe end-users. Exploring the legitimation of newness in these two distinct contextsprovides insight into how various forms of newness are legitimized in differentenvironments. The study is then guided by the question: How are new products,ventures, and sectors legitimized in different institutional settings? In the gamblingcontext, the study investigates the co-emergence and co-legitimation of new firmsin transformed sectors. In the life science context, the focus is on legitimation ofnew products in different institutional settings. The study consists of five papers toaddress this question and is conducted qualitatively using single and multiple casestudies in the different contexts explored. The study manages to identify four formsof new venture and sector co-emergence: benign, supervenient, radical, andnominal. The findings suggest that leaders can apply feedback loops,conformance, familiar cues, and repetition and consistency strategies to legitimizethe co-emergence of newness during the edge of chaos. To legitimize new productsin different institutional settings, findings suggest that different legitimationstrategies are to be used when introducing new products in different markets. Emphasis is also placed on developing internal legitimacy before developingexternal legitimacy when launching new products in uncertain markets.