Companies are facing pressure in order to reduce their environmental impact.However, the managerial tools and frameworks to bring sustainability into practice are in their infancy. This paper is encompassed on the development of the Theory of Corporate Sustainability, and this work offers the practical implication of the theory to provide researchers and managers with a tool to analyse how companies integrate sustainability among their strategies and operations. The methodology has been based on the use of the case-study protocol. Four interviews have been carried out and data obtained has been analysed using content analysis methodology. Resultsshow that companies that have a formal structure to deal with sustainability are able to integrate sustainable practices in a higher degree than companies that adopt sustainability in a siloed way. Moreover, this paper shows how the process of sustainability integration differs between existing companies and new companies.