The theoretical relationship

which correlates the glass transition temperature (Tg) with the other molecular parameters

has been proposed by taking the dynamic segment as the basic statistical unit. The dependency of Tg on the stiffness factor o2(Tg) for isolated chain at Tg and dynamic stiffness parameter (B= -d(lno2)/dT) has been discussed in detail. The theoretical prediction is compared with the experimental data for many linear polymers and the good agreement is obtained. It has been shown that Tg is essentially governed by the chain stiffness factor at Tg.