Following Stell, one can determine the pair correlation function h(r) of the hard sphere fluid for all distance r by specifying only the tail of the direct correlation function c(r) at separation greater than the hard core diameter σ . More recently, Katsov and Weeks extended Stell ideas to describe the structure of continuous fluids containing repulsive and attractive parts like Lennard-Jones and Yukawa fluids. In this paper, we extend these ideas to determine the structure and thermodynamics of square well potential from the tail of the direct correlation function. This potential is used essentially to model complex systems like polymers and colloids. We use the Martinov-Sarkisov bridge functions in the closure relation. An efficient numerical algorithm is used based on Labick procedure. We give results for the structure and thermodynamics at different values of the width of the square well potential, and at different thermodynamical states.