In the past few years we have seen the near collapse of the world financial system, and we still have yet to find solutions for world poverty or the food crisis. People have started looking for new solutions in order to solve these problems and are considering new employment options besides the traditional for-profit business sector. Employees are increasingly looking for work in organizations that have a more sustainable approach to business. One organization type that fits these criteria is a social business. Most of the research in social entrepreneurship and social businesses, however, has concentrated on the social entrepreneur and the entrepreneurial process so far. Only few studies have explored the employee side. Similarly, research on perceived employee motivation has mainly concentrated on the traditional for-profit businesses and on non-profit organizations. Although employee motivation is considered as crucial to the success of any business, perceived employee motivation in established social businesses has scarcely been researched yet. The purpose of this thesis is to understand why people choose to work in a social business, and what motivates them to work there. This research was conducted as a single case study following Stake (1995). It was carried out in the Helsinki Metropolitan Area Reuse Centre Ltd in Finland. In order to achieve our goal, we have found it helpful to combine relevant motivation theories such as intrinsic motivation, task significance, prosocial motivation, value congruence, and meaningfulness, with current social business theories. As a result of our research, we have developed a model that elaborates how employees make their decision on employment and what influences their perceived motivation. Our findings suggest that both, the distinct business model and the mission of a social business have a great impact on people’s choice of employment. Moreover, the company values, which are partly derived from the mission of a social business, also influence prospective employees’ choice of employment. In addition, the employees’ educational background impacts their choice as their values reflect their education. They are also looking for such work, whose content fits their education. In our study we have tried to point out that perceived employee motivation in a social business is also strongly influenced by value congruence. Moreover, the perceived meaningfulness that derives from the social business’ mission has an impact on the perceived employee motivation. The employees feel that their work is positively affecting people, society, and the environment, which results in task significance and prosocial motivation. Finally, the flexibility of the work, the ability to influence the work content, and the work atmosphere, are also shown to exercise a great influence on perceived employee motivation.