ABSTRACT: Bilingualism is the habitual use of two languages by one person; in its purest form the two are quite separate. Its attainment is not marked by the crossing of a boundary but by a gradual transition, the earliest stages of which can be valid within limits. On its inner side, bilingualism relates to preverbal thought, making available to the speaker two separate systems of expression. The best place for the development of bilingualism is the home. The next best place is the classroom, but only if it provides ample practice in face-to-face communication. An exclusively philological approach does not encourage the separation of the two language codes. An all important ingredient in helping the learner gain control of the new language as an entity separate from the mother tongue is the dyadic factor—the behavior two individuals considered as one.