This bachelor thesis in business economics raises the topic about Corporate Responsibility (CR), this topic is currently being discussed in a variety of channels and today an increasing number of companies are involved in corporate responsibility. How do Skanska work with sustainability and why are they doing this? It is also important to see the results of the work with sustainability will lead to. We will go into more depth in one of Skanska's projects, project M25, to investigate the CR strategies they use and see how they actually work with sustainability. The purpose of this paper is to describe and analyze how and why Skanska is working to implement CR policies in their operations and more specifically from the M25 project in order to achieve sustainable business development. Our main questions is; how and why does Skanska implement sustainability in their business and in the project M25 and what can the outcome of this sustainability lead to? The study is based on a qualitative method, we performed both an unstructured personal interview and a semi-structured interview. This is to get a deeper understanding of how and why the company Skanska is working on sustainability. We have done a literature study and we selected different theories and also used various documents from Skanska. Our conclusion is that Skanska uses several different strategies to achieve sustainable business development, for example, they have developed their own voluntary rules, follow different directives and standards and they have developed various techniques and tools. The conclusions we have drawn is that Skanska is working actively to identify its stakeholders and also takes account of stakeholders who do not have a direct link to the business. They work in a proactive manner through education, investigation and monitoring to achieve a sustainable business. Skanska has agreed that they are part of a larger context in which they affect individuals and agents. Skanska and the society will receive various benefits depending on which CR strategies Skanska uses.