The Mondragon Cooperative Experience has been one of the worker-owned alternative organizations that has received the most attention in the academic world. Despite its economic success, this experience has also been wrought with its own share of tensions and internal paradoxes. Surprisingly, the perspective of worker–member–owners in the analysis of those inconsistencies in Mondragon has been given very little prominence. Similarly, the equivalence between the formal policies defined in that experience and the day-to-day activity has been widely taken for granted in the literature. This article aims to fill this gap and contribute to the literature by analyzing the extent to which Mondragon’s basic cooperative principles are applied in the daily practice from the perspective of worker–member–owners. To that end, in-depth interviews were conducted with worker–member–owners of Mondragon outside their working environment. An interpretative analysis provides evidence of a decoupling of cooperative principles from the workers’ daily activity. Furthermore, a tacit and non-formal principle frequently surfaces in the interviews: the principle of the primacy of secure membership and guaranteed employment. This seems to be the most solid tie that binds members to their organization, in a context with growing individualization and precarious employment conditions, together with a ubiquitous managerial discourse that encourages shallow forms of workplace participation. This work contributes to the broader field of organizational theory and sheds light on the dissociation process in formal policies of organizations governed by alternative founding principles. It also tries to contribute to the study of the sustainability of such alternative organizations.