  We define a class of pseudo-ergodic non-self-adjoint Schr\"odinger operators
acting in spaces $l^2(X)$ and prove some general theorems about their spectral
properties. We then apply these to study the spectrum of a non-self-adjoint
Anderson model acting on $l^2(\Z)$, and find the precise condition for 0 to lie
in the spectrum of the operator. We also introduce the notion of localized
spectrum for such operators.
