This paper focuses on Reusability. Reusability is one of the most significant software quality indicator its correct quantification directs to the prospects of facilitating as well as improving the software maintenance process.  Reusability is strongly related to maintainability and constantly plays a key role to deliver high class maintainable and trustworthy software within time and budget. In this paper, an endeavor has been made to establish a correlation between object-oriented design constructs and Reusability. A Reusability Quantification Model (RQM^OOD) has been proposed for Object-Oriented Design by using multiple linear regression. Finally, the proposed model has been validated using an experimental tryout.