Functional Specification of software systems has gained immense importance in the present competitive world of developing software more quickly, more efficiently and more accurately. Functional Specification activity is carried out mainly at Requirement specification and analysis stage and is continued in design phase as well. Formalization of functional specification along with consistency verification and automated execution constitutes some of the major domains of research. Object oriented features of software systems pose greater challenges to people related to software industry as many traditional techniques remaining inadequate or inefficient for specifying functionalities of a software system. In this work we propose new methods and frameworks to help in specifying behavior of object-oriented software system more effectively during the different phases of development.