C\'esar R. de Oliveira, Marcus V. Lima Singular Continuous Nonprimitive Operators]{Singular Continuous Spectrum for a Class of Nonprimitive Substitution Schroedinger Operators (38K, LaTeX 2e) ABSTRACT. We present a class of discrete Schr\"odinger operators, with potentials derived from nonprimitive substitutions, that has purely singular continuous spectrum. We give sufficient conditions on the substitution rule assuring singular continuous spectrum, either for a generic set in the hull of the potential or for a set of total invariant measure.