This research deals with a repertoire of collective practices in a community of transfeminine sex workers in urban Turkey. Some of the practices discussed in this thesis refer to building a community, communal spaces, social codes, and relationships which enable trans sex workers to support and protect one another. Other practices can be read as commitments and expressions that challenge violence and marginalization. The research has been carried out within the context of the broader debate on urban marginality. While some studies on this topic have focused solely on its constraining effects, others have overemphasized the enabling potential of margins, romanticizing the solidarity and political agency that emerges in these spaces. Building on a middle position between these two perspectives, my research primarily focuses on the possibilities created at the urban margins, together with specific structural factors. Based on participant observation, semi-structured interviews, and online sources, I begin by explaining the socio-political, legal, economic, and spatial context of trans sex workers in contemporary Turkey. I argue that the ambiguous nature of marginality with respect to these aspects facilitates their alignments and informal ways of organizing. I then investigate the shared spaces, relationships, collective subjectivities, social codes, and labor organization of a specific community of trans sex workers. These structures form the basis of their exchanges of support and community mobilization, and help the community to address its common challenges. I go on to analyze how this population generates a range of struggles, namely, collective protests and individual confrontations, to counter violence and marginalization. Finally, I explore the defying and community-building roles of the shared humor, joy, and laughter that permeate everyday social interactions among sex workers. This thesis makes three original contributions. It shows that urban marginality, albeit less focused, is a critical component in the lives of trans feminine sex workers in Turkey. Secondly, it proposes that gender and sexuality, which are largely overlooked in urban studies, are relevant and significant analytical categories for both urban subordination and politics. Finally, the thesis suggests that urban margins which facilitate alignments and informal means of organizing among people, also constitute the spaces where tensions and ruptures can emerge, and expressions of solidarity and struggle can become fragile. Thus, my research offers a nuanced understanding of urban agency by explaining the material, relational, and discursive opportunities it creates and the complexities and ambivalence that can occur at the margins. Despite their limitations, the collective practices described here support the material and social persistence of sex workers. This is done by establishing communities and friendships, mutual care, claiming visibility, earning a living, and creating joy in the face of the persistent violence, discrimination, and stigma that encircle their lives.