This study aims to assess the efects of optimism and self-eicacy on entrepreneurs who intend to reform their market. Drawing on cognitive and institutional theory, the factors of optimism and self-eicacy were selected to beter understand the association between entrepreneurial cognition and opportunity creation. This is a qualitative, multicase study where six Turkish entrepreneurial irms in the process of reforming and redeining their markets through new value creation, were selected on the basis of purpose sampling. While both optimism and self-eicacy signiicantly motivated entrepreneurs to create new value propositions, the efects of these factors varied across cases. In the sampling, all irms associated value creation with innovation. Moreover, irms tended to use informal/formal networks to create new value propositions and change current legitimacy. Only limited studies have reported on the efects of institutional environments and cognitive structure of entrepreneurs on value creation, particularly within emerging markets. Moreover, the concept of value creation, which involves redeining and reshaping the present market, is not recognized within either cognitive or institutional theory. Optimism and self-eicacy have previously been considered as independent concepts in the literature. However, in the current study, the two concepts are interrelated, thus contributing to the literature of entrepreneurship.