Alexander Elgart and Jeffrey H. Schenker A strong operator topology adiabatic theorem (34K, LaTeX 2e 2e ) ABSTRACT. We prove an adiabatic theorem for the evolution of spectral data under a weak additive perturbation. For continuous functions of the unperturbed Hamiltonian the convergence is in norm while for a larger class functions, including the spectral projections associated to embedded eigenvalues, the convergence is in the strong operator topology.