A Hermitian random-matrix model with an arbitrary Gaussian distributio
n of the matrix elements is proposed and studied by means of effective
-field theory. We construct an effective action as a functional of the
eigenvalue distribution. Using this effective action, we obtain the e
ntire N-level distribution function in the mean-field approximation. W
e show a smooth transition from the Gaussian Unitary Ensemble to the P
oisson level distribution in the same delocalized phase. The connectio
n to previous results is discussed.