The theories, 2)-planatory models and conceptual systems of Latin American social Science are facing a serious crisis. It might appear that the main reason for this crisis is that the Area is undergoing various and new processes of change which may not be understood in the light of the old theories. then need to PLaborate new theories and explore the use of new concepts. The term Metamorphosis' might become a part of the regular language used by the social science. It might b used to identify a no mi: processes, which are relatively reversible, of social or urban change, of change of shape and/or function, generally due to an exogenous action, involving loss of balance, internal feed-back and, partially, of identity. The changes occurred in Santiago during the authoritarian Period (1973-1989) may constitute an evident example of this kind of metamorphosis. A democratic city, with acceptable satandardc, of life, was changed into a hostile city, with a high social segregation of its space and a deterioration of the standards of life, in particular of the majority, which was achieved through an authoritarian rearrangement of the space and private appropriation of the public space. The new democratic transition government has begun to apply some policies to reduce the urban deterioration. However, these problems are of such magnutude that they might not be solved without the effective, institucionalized participation of the citizens. Only through a democratic, non-burocratic planning, it would be possible to direct the use and growth of th city.