This dissertation examines architectural operations developed from the 1950s through the 1980s that challenged modernity’s “anxiety of contamination” and that have negotiated the boundaries between the realm of the individual and the social, the expert and the mass men, the local and the universal, modernity and the vernacular. The central project of the dissertation is to present ambivalence, "thirdness", and “strangeness” as conditions that activate the creative power of conflicts in negotiating binary polarities. The research is supported by a special focus on the Portuguese architectural design and theory and its relation with the societal transformations that ensued from the late 1940s until the early 1990s. Throughout this period, the world in general and Western Europe in particular lived under the all-encompassing polarity triggered by the postcolonial geopolitics and the Cold War. In this context, Portugal's position at the semiperiphery of the world system, i.e. simultaneously located at the periphery of the core and being the core for the periphery, generated a productive outcome from the entwined relation between modernity and the vernacular that pervaded the disciplinary debate in general and the architecture of dwelling in particular. Firstly, the dissertation analyses in detail the work of the Portuguese CIAM group and its most prominent members and followers, underlining their negotiation of the universal tenets of modernity with the ethos of local culture. From the aftermath of WWII until the emergence of the protest movements in the late 1960s, their work went beyond a pastoral vision of the vernacular tradition, contributing to negotiate the mechanist tropes of architectural modernism with the development of a humanistic approach to the habitat for the masses. Then, the purview of the research moves to the work of a single architect, Álvaro Siza, examining how his housing projects designed and developed from the 1970s through the 1980s, in Porto, Évora, Berlin and The Hague, tackled the disciplinary challenges brought about by a pervasive contestation on hegemonic powers. In this period, Siza’s work asserts the vital role of the architectural project to activate collective memory and to confront a counter-pastoral view of modernity. The research suggests that a critical articulation between architecture’s disciplinary codes and conventions and the specific aspects of the situation contributed to create a contaminated landscape, bypassing the shortcomings of social, political, and disciplinary constructs based on polar oppositions. The conclusions of the dissertation assert the importance of activating collective memory, coping with contingency, and the creative potential of ambivalence and conflicts, as vital contributions to frame disciplinary approaches prone to yield a negotiated outcome in contexts dominated by hegemonic relations and the rhetoric of binary polarities.