We study the dynamics of a tagged particle in an infinite particle environment. Such processes have been studied in e.g. [GP85], [DMFGW89] and [Osa98]. I.e., we consider the heuristic system of stochastic differential equationsThis system realizes the coupling of the motion of the tagged particle, described by (TP), and the motion of the environment seen from the tagged particle, described by (ENV). As we can observe in (TP) the solution to (ENV), the so-called environment process, is driving the tagged particle. Thus our strategy is to study (ENV) at first and afterwards the coupled process, i.e., (TP) and (ENV) simultaneously. Here the analysis and geometry on configuration spaces developed in [AKR98a] and [AKR98b] plays an important role. Furthermore, the harmonic analysis on configuration spaces derived in [KK02] is very useful for our considerations.First we derive an integration by parts formula with respect to the standard gradient ∇ Γ on configuration spaces Γ for a general class of grand canonical Gibbs measures µ, corresponding to pair potentials φ and intensity measures σ = z exp(−φ) dx, 0 < z < ∞, having correlation functions fulfilling a Ruelle bound. Furthermore, we use a second integration by parts formula with respect to the gradient ∇ Γ γ , generating the uniform translations on Γ, for a (non-empty) subclass of the Gibbs measures µ as above which is provided in [CK09]. Combining these two gradients by Dirichlet form techniques we can construct the environment process and the coupled process, respectively. Scaling limits of such dynamics have been studied e.g. in [DMFGW89], [GP85] and [Osa98]. Our results give the first mathematically rigorous and complete construction of the tagged particle process in continuum with interaction potential. In particular, we can treat interaction potentials which might have a singularity at the origin, non-trivial negative part and infinite range as e.g. the Lennard-Jones potential.