Landim, C., Volchan, S. B. Equilibrium Fluctuations for a Driven Tracer Particle Dynamics (605K, Postcript) ABSTRACT. We study the equilibrium fluctuations of a tagged particle driven by an external constant force in an infinite system of particles evolving in a one-dimensional lattice according to symmetric random walks with exclusion. We prove that when the system is initially in the equilibrium state, the finite dimensional distributions of the diffusively rescaled position $\sqrt{\epsilon} X(\epsilon^{-2}t)$ of the tagged particle converges, as $\epsilon \rightarrow 0$, to the finite dimensional distributions of a mean zero Gaussian process whose covariance can be expressed in terms of a diffusion process.