The possibility of determining cosmological parameters on the basis of a wide set of observational data including the Abell-ACO cluster power spectrum and mass function, peculiar velocities of galaxies, the distribution of Ly-[FORMULA] clouds and CMB temperature fluctuations is analyzed. Using a [FORMULA] minimization method, assuming [FORMULA] and no contribution from gravity waves, we show that this data set determines quite precisely the values of the spectral index n of the primordial power spectrum, baryon, cold dark matter and massive neutrino density [FORMULA], [FORMULA] and [FORMULA] respectively, the Hubble constant [FORMULA]km/s/Mpc) and the value of the cosmological constant, [FORMULA].