Sustainability is becoming increasingly more important for companies as the public demands that companies are more transparent and act in a responsible manner. This thesis researches what role management control systems play when implementing and working with sustainability. This was done by interviewing CSO’s and controllers as well as examining annual financial and sustainability reports at three large Swedish firms, all praised for their sustainability work. The data was compared between the case companies and analysed by using the management control systems framework by Malmi and Brown (2008). The findings show that the cultural controls coupled with the administrative controls have the most important role to play when implementing sustainability, as they provide the basis for the other control systems. These other control systems have currently a much smaller role to play as there are still challenges connected to sustainability that hinder the use of these control systems to their full potential. The findings further show that the key to implementing sustainability lies in the company’s ability to find and create business cases concerning sustainability as this help aligning the sustainability goals with the business goals and overall strategy.