This section introduces a co-rotational (CR)-based secant matrix procedure for conducting elastic postbuckling analysis of truss structures. The co-rotational approach reduces the complexity of nonlinear problems by isolating rigid body rotations and translations and considers only the local deformations of the truss members. This chapter explains the implementation of the secant matrix method onto a CR framework. Several numerical examples of different truss systems are presented. In this chapter, individual member postbuckling expressions are derived using which interaction problems of member and global buckling are solved. Although some problems use synthetic data, they provide much-needed information on the underlying postbuckling phenomenon.