Community of practice (CoP) is defined as a potential space for cooperation between peers favoring the access to knowledge and allowing the development of innovation. A CoP, which can also be seen as an informal network of cooperation, could be interesting for startups that suffering with the lack of resources and that are deficient in their innovation process, especially when they are far from potential innovation partners. However, the issue of competition cannot be disregarded in their inter-organizational context. Furthermore, the literature on communities of practice has not yet addressed this paradoxical dynamic in which there is presence at the same time of cooperation and competition logics. Moreover, the literature of coopetition does not well explore this kind of dynamics in informal networks. Thus, the goal of this thesis is to study the effect of coopetition on the social dynamics of inter-organizational CoPs in an innovation context. This study is based on an exploratory and longitudinal case study that was conducted at San Pedro Valley (Brazil), which is a CoP of innovative startups in the information technology sector. The analysis of this case study allows us to construct a categorization of different relationships of coopetition that exist in the inter-organizational CoP. Even if the participation of entrepreneurs, which are members of this informal network, allows the strategic adjustment of their companies in issues related to the innovation projects, some relations will progressively modify the crucial characteristics of the CoP due to the forthcoming of tensions and conflicts. One of the main results of this thesis is a new light at the functioning of CoP at the inter-organizational level showing how the coopetition strategies is developed in informal networks. Another result includes an individual-level to understand the drivers of coopetition, and then the study provides insights about the informal relationship in the scope of coopetition strategy. It is also worth mentioning methodological contributions based on the use of a "netnography" approach to entrepreneurial social networks, as well as managerial contributions to entrepreneurs, allowing a better understanding of their innovation ecosystem.