The calculated polarizabilities α and hyperpolarizabilities γ of some amides are reported. The effect on these properties of methylation, bonding and nonbonding interactions, and isomerism, has been analyzed. Some aggregates of formamide have been considered and the cooperative character of the intermolecular interactions is demonstrated. The effective properties (α and γ) of several functional groups, associated with the examined amides, were studied using an appropriate index. The established order for the relative polarizabilities of the considered functional groups is: NH2OC<HCH3N<(CH3)2N<NHCH3OC<N(CH3)2OC while the relative hyperpolarizabilities follow the order: HCH3N<(CH3)2N<NH2OC<NHCH3OC<N(CH3)2OC. The computations have been performed by employing the CHF-PT-EB-CNDO method. This procedure gave, for the considered amides, polarizability values which are in satisfactory agreement with experimental data (theoretical and experimental values differ on average by 9.4%).