2010/2011 ; Quality is one important characteristic of products and services, but customers can find some difficulties in evaluating it. If information is not uniformly distributed (e.g. sellers have more information than buyers), trade can be difficult (Akerlof 1970). Certification, defined as the assurance that certain requirements are respected, is a possible mechanism to mitigate the asymmetric information. A typical example of certification is the university degree that assures of the fulfillment of academic requirements. This thesis focuses on the ISO 9000 certification, which assures that the quality management system respects the requirements of the ISO 9000 standards family. Having been adopted by more than 1.000.000 organizations in the world, ISO 9000 is a well-known family of standards based on Total Quality Management, a managerial approach aimed to improve quality and organization performance. Several studies investigated ISO 9000 focusing mainly on the manufacturing sector where ISO 9000 originated. However, over the last years, ISO 9000 has being increasingly adopted in service sector. The current study contributes to this research stream taking on both qualitative and quantitative methods to investigate the adoption and the impact of ISO 9000 certification in services. More precisely, the thesis focuses on two main research questions: Why do companies choose to be ISO 9000 certified? What is the relationship between ISO 9000 and innovation? The two research questions are investigated through the lens of the signaling model of education (Spence 1973, Weiss 1995). According to this framework, education can benefit the employee directly by increasing his expertise of an employee and by indirectly signaling his unobserved but relevant abilities (e.g. persistence). Similarly to education, ISO 9000 can improve organization performances and ISO 9000 certification can signal unobservable abilities of better companies. Some implications are drawn from this theoretical framework and they are tested using ...