In this study we will discuss the historical changes in the work and life relationship which resulted in development of new theories. After an introduction to work-life relationships, different theories of work and life are presented in the second section of this paper. These theories are categories intro three generations based on their characteristics in the historical evolution of work-life studies. In the third section measures of work and life spillovers are described. In section four, critiques of the current methodologies which is being used in the work and life studies are presented. Discussion section which is presented in following section includes some arguments regarding the ways to select the most appropriate theories for work-life studies. Also in this section some recommendations are presented for enhancing the commonly used methodologies of the research on work and life relationships. Finally, in the last section, some recommendations for future studies are presented.