The authors present recent developments in spectral conditions for the existence of periodic and almost periodic solutions of inhomogenous equations in Banach Spaces. Many of the results represent significant advances in this area. In particular, a new approach based on the so-called evolution semigroups with an original decomposition technique is systematically presented. The monograph also includes extensions of classical methods, such as fixed points and stability methods, to abstract functional differential equations with applications to partial functional differential equations.