This thesis seeks to contribute to knowledge on how sameness and difference play out in personal and professional South-South relations, through an ethnography of interactions between Brazilian and Mozambican development workers, in the HIV&AIDS and gender fields, in Mozambique. The thesis is structured around nine chapters. The introduction outlines the research context, the conceptual frameworks, the key terminology used in the thesis, as well as how my personal and professional life-story inspired this research. In Chapter Two, I discuss the research methodology, sites and spaces, describe the process of multi-sited ethnography in Brazil and Mozambique and reflect about my positionality. The main body of the thesis moves from the macro to the micro level. Chapters 3 and 4 map the reproduction of development and knowledge hierarchies within South-South cooperation institutional discourses and practices and the production of a political economy of opportunities and international mobility for Brazilian development workers. The following chapters discuss how difference and sameness, proximity and distance, and horizontality and verticality are experienced in interactions between Brazilian and Mozambican development workers. Chapter 5 explores principal ways in which the notion of kinship structure relations and imaginaries. Chapter 6 examines affinities, hierarchy and power in an International Non-Governmental Organisation office in Maputo, while Chapter 7 discusses political affinities in feminist knowledge practices. I then analyse the interconnections between the personal, professional and political (Chapter 8) through examining the potential for professional relationships to evolve into something more personal. Chapter 9 concludes the thesis with a review of my findings in the light of the main research question and outlines this thesis' contribution to academic debates on feminist organising, aid ethnographies and South-South relations.