This paper provides an overview of the author's Ph.D. thesis that presents a framework for providing quality based re-engineering of object-oriented systems [12]. The framework allows for specific design and quality requirements (performance and maintainability) of the target migrant system to be considered during the re-engineering process. Quality requirements for the migrant system can be encoded using soft-goal interdependency graphs and be associated with specific software transformations that need to be carried out for the specific target quality requirement to be achieved. These transformations can be applied as a series of the iterative and incremental steps to the source code. An evaluation procedure can be used at each transformation step to determine whether specific goals have been achieved.