This paper aims to deepen the understanding of the mechanisms triggering radical innovation in large firms by exploring the impact of social interaction on the fuzzy front end. The provided information shall help managers and innovators in large firms to analyse their existing innovation ecosystem and identify its shortcomings. This work will not only contribute knowledge about key influencing factors but more importantly about the holistic context in which those factors are nurtured in order to increase the firm's radical innovation performance. The outcomes of a conducted literature review are used to develop a framework, which present the dynamics and relations between several components critical for the success of radical innovation. These components are influenced by several factors, which are identified, listed and discussed. Subsequently a graphical presentation is created to indicate the complex interrelations between those factors. ^The framework and its influencing factors are finally tested in a case study using qualitative research methodology. The subject of the case study is a disruptive innovation project at a large, multinational supplier to the pharmaceutical industry. The literature review shows that the fuzzy front end has the highest impact on radical innovation success, but is characterized by high uncertainty and discontinuity of the existing status quo. In that environment, it needs imagination of the future or market visioning competence; an ability, intuitive and creative individuals possess. Hence, those individuals are able to recognize a need or an opportunity. By social interaction with internal and external peers, ideas can be generated and evaluated. Through identifying and testing possible solutions (solve problems) new knowledge is created and new learning takes place. ^Further social interactions within the firm transfer these learnings into new organizational procedures, strategies and culture. By that process of organizational learning, a continuous renewal and implementation of learnings occurs and influence in turn the fuzzy front end of new radical innovation projects. The identified factors influence that genesis of radical innovation by supporting either a necessary prerequisite or by being part of the social interaction dynamics itself. Prerequisite factors are necessary on the individual level (personal traits, cognitive and creative ability, prior knowledge and experience, ) as well as on the organisational level (resources, stimulating work environment, encouragement, culture,...). ^Which influencing and enabling factors are most important for a specific firm's setting, will depend on many case specific aspects, such as the nature of the industry the firm is serving, the company's risk appetite or the firm¿s current innovation culture and procedures. Thus, a generic conclusion on the most important single factor or factor group can and should not be made. Nevertheless, there are a few universally valid conclusions resulting from this study: (1) Certain personal traits and preconditions favour creativity, social interaction and problem-solving activities. While one may not know in advance which technology and prior knowledge will be of interest, there is evidence to predict which personality traits will be crucial to pursue radical innovation. Diversity and open innovation networks can help hedging the firm's technological capabilities. (2) Social relations, (informal) exchange of knowledge, experiences or mental models need trust between peers to emerge. ^Creating trust to exchange, taking time for sense making and transfer of sticky knowledge, joining activities in a shared space, all this takes time, space, physical contact and above all, it takes a continuous approach and support from the firm's management. (3) Radical innovation cannot directly be enforced to happen, but with the right managerial and leadership decisions the probability for radical ideas to emerge and radical innovation to succeed can be increased significantly.