The task of contrastive analysis is to discover underlying similarities in the deep structure of two languages and the rules which provide language specific features on the surface. Within the model of a transformational grammar identifying syntactic primes and basic proposition rules in the deep structure together with rules for the realization of surface constructions, i t can be demonistrated that the language specific English and Italian imperatives rest on the same underlying deep structure. A unified set of rules marks the progression from a set of common primes and syntactic relations to different surface realizations for the two languages. Contrastive statements of this type, accounting for both similarities and differences, become useful in language teaching for learning problems arise in the deep to surface realization or stylistic rules operating on the lower nodes of the underlying deep tree structure. Explicating surface relationships through recognition of the relation between deep and surface structures makes possible a more explicit contrastive analysis.