Recently, there have been major developments in the nonlinear systems theory for the regulation of nonlinear time-invariant systems. In this paper this methodology is extended to nonlinear rime-varying systems. First, the relevance of modeling systems in chemical engineering with time-varying parameters is shown. Then, modified Lie derivatives are defined to account for the explicit time dependence of the system model on ti!ne. A time-dependent invertible coordinate transformation is derived to quantify the zero dynamics of the system. State feedback laws are synthesized, which provide a linear time-invariant input-output response. It is observed that the internal stability of this state feedback is not analogous to the results of the time-invariant case. A dynamic output feedback controller for the time-varying system is synthesized. This methodology is used to derive feedback laws for the regulation of linear time-varying systems. Finally, the proposed methodology is illustrated by a simulation example.