  In the framework of the Tsallis nonextensive statistical mechanics we study
an assembly of N spins, first in a background magnetic field, and then assuming
them to interact via a long-range homogeneous mean field. To take into account
the spin fluctuations the dynamical field coefficient is considered to be
linearly dependent on the temperature. The physical quantities are evaluated
using a perturbative expansion in the nonextensivity parameter (1-q). The
extended Curie-Weiss law in the mean field case has been generalized. The
critical temperature and the Curie- Weiss constant are found to be dependent on
the nonextensivity parameter (1-q).
