The scientific concepts and principles pertinent to lake restoration do not essentially differ from those of classical limnological research in general. The more specific question of their applicability to practical lake management, therefore, is not so much one of further addition to, but one of appropriate selection from the list already available. Nonetheless, the process is a dynamic one: Principles and concepts evolve as science is evolving and, as a consequence, approaches and perspectives may change with time, as well as mode and technologies of their application to practical problems. For this reason, in the following, no attempt is made to discuss current restoration techniques and measures, or their underlying scientific principles, as these can be found in limnological textbooks. Also, more specific aspects o f current experience in lake restoration are presented in other presentations of this symposium. Instead, I shall try to provide a perspective to how, and in what way current scientific principles and concepts can be visualized within a synthetic framework pertinent to lake research and lake restoration. With the selection o f the arguments which I wish to explore, only part of this vast and complex subject area can be covered. After having set the stage, I will discuss, in the first half of this paper, some of the essential lead concepts. In the second half, I will focus on aspects which are important in designing research programmes. Because of limited space, references to only a few examples will be made, and some of the subjects unavoidably will remain sketchy.