Due to increasing pressures from stakeholders, organizations face important challenges that require them to move from compliance to proactivity regarding sustainable development. They aim to adjust their strategy accordingly and reflect how they are addressing sustainability in their business. Realizing sustainable development at strategical level requires change. In the same time strategy needs to be translated into operational activities in order to create tangible results. This thesis explores the potential of projects as essential change instruments in realizing this strategic desiderate. We conducted a series of ten interviews with top managers in relevant organizations in Sweden in order to analyze their perceptions on this requirement. Our findings point out the importance of applying sustainability perspective in selection of project portfolios and project management processes. We also emphasize the catalyst role of organizational learning and sustainability awareness among employees which can lead to a sustainability culture within organizations.