In recent years excellent opportunities to discuss the concepts of reuse, re-functioning, rehabilitation, revalorization, re-adaptation, recycling in architecture in a broad sense both in academic area and in practice have occurred. These concepts, which aim to improve living quality and describe a participatory functional model and thus create sustainable spatial transformations, differentiate from the concepts of restoration, reconstruction and renovation with regard to these characteristics (Uçkan, 2000). Using recent technological tools, architects and urban planners have been working to improve the urban areas and historic buildings that have been abandoned under the economic, social and technological developments, trying to integrate them into city life with new functions. Developments in Canary Wharf in London, on the site of the Expo 98 exposition and its surroundings in Lisbon, or in IBA-Emscher Park in Ruth are examples from these kinds of transformations in urban scale. In the building scale there are also several attempts for transformation of old palaces, public buildings, religious and industrial structures into some cultural constructions such as museums, exhibition halls, restaurants and cafes’ and some educational, residential buildings. The Tate Gallery and renovations in the British Museum in London, the New German Parliament in Berlin, and the gazometer projects in Vienna are some implementations based on this concept.On the other hand changing needs and technological and economical necessities make “re-evaluation of existing contemporary buildings” a current issue. Nowadays, architects meet both the designing of new buildings and the complete or partial development of existing buildings to improve living quality and to use spaces more effectively based on the changing needs, requirements of the new century. J. Nouvel (1993) states: “Today the city has to be developed in small touches: by iteration, alteration or revelation”. Similar to his statements, in the future it might become inevitable to reflect changes in living patterns to spatial formation and to develop buildings both with and within their skins with new discoveries taking into account changing needs, social, cultural, economic, scientific and technological developments with these new discoveries. Certainly the concept of re-functioning of existing buildings will be totally differentiated from the new building proposals with their specific problem areas. The problem of integration of a new proposal to the existing layout without disturbing its identity and living pattern will accompany the problem of structural constraints that affect new design proposals. In the design process, the concept of flexibility will also become an issue for further developments. While scale, function and technological characteristics will require different expressions for the proposal in the design process, the “problem of sustainability of life in existing buildings with new touches” will remain constant in all cases.These types of transformations have been carried out in Istanbul Technical University (ITU) campuses in recent years. Keeping abreast with modern developments, ITU is constantly restructuring itself and renovating its physical, educational and social infrastructure. ITU’s Ayazaga Campus which started to develop in the 1970s, today encompasses seven faculties, five institutions, the president's office, the department of physical education and sports, the library, a conference hall, health, sport and food centers, residences and dormitories. This paper focuses on the post occupancy evaluations in the student social centers of the two faculty buildings of Istanbul Technical University, Ayazaga Campus, which were designed (by the authors of the paper) in the extent of renovation attempts of badly used or abandoned spaces. The aim of designs is to transform the existing and useless canteen and service spaces into student social centers while providing various activities and integrating the spaces for the faculty and campus life.Evaluation studies are usually undertaken to assess the adequacy of existing environments and to provide guidance for the creation of new environments (Zube, 1984). Evaluation differs from architectural criticism by being data based, by being more than the simple reflection of one person, and by addressing more than aesthetic issues (Wener, 1989). On the other hand, post-occupancy evaluation is the process of evaluating buildings in a systematic way after they have been built and occupied for some time. Post-occupancy evaluations focus on building occupants and their needs, thus providing insights into the consequences of past design decisions and the resulting building performance (Preiser, et al., 1988). Consideration of appropriate methodology in a post-occupancy evaluation is an important issue. In this study a multi-method approach has been adopted to enhance the credibility of findings. Qualitative techniques of data collection such as in-depth interviewing with administrative and teaching staff, and with students, behavioral observation, and behavioral mapping, photographic documentation are employed in the post-occupancy analysis. This study will give a chance to the architects to evaluate their own designs based on criticism of their real users. Similar projects in two different cases will be comparatively tested and the findings will provide feedback for further developments in other ITU faculty buildings.