In this paper we will describe recent theoretical approaches to calculating the response of multielectronic atoms in intense laser fields. This work is based on the soultion of the time–dependent Schrödinger equation for a single atom driven by a linearly polarized laser field. Results obtained in recent experimental measurements of multiple ionization rates suggest that the interaction between the electrons in helium enhances the double ionization rate. Solving the full two–electron Schrödinger equation is a very computer–intensive problem, and therefore we have introduced a new model that can reproduce the experimental results. This model is described in detail in this paper, and used to investigate the origin of the double ionization.