In order to support the maintenance of object-oriented software systems, the quality of their design must be evaluated using adequate quantification means. In spite of the current extensive use of metrics, if used in isolation, metrics are oftentimes too fine grained to quantify comprehensively an investigated aspect of the design. To help the software engineer detect and localize design problems, the novel detection strategy mechanism is defined so that deviations from good-design principles and heuristics are quantified in form of metrics-based rules. Using detection strategies an engineer can directly localize classes or methods affected by a particular design flaw (e.g. God Class), rather than having to infer the real design problem from a large set of abnormal metric values. In order to reach the ultimate goal of bridging the gap between qualitative and quantitative statements about design, the dissertation proposes a novel type of quality model, called Factor-Strategy. In c...