Bilingualism is a common phenomenon in India. We are all instinctively bilingual. A large proportion of the world's population is bilingual. A bilingual speaking to the other bilingual chooses the language unconsciously or semi-consciously with no extra time or effort. Language alternation has become significant in the Indian context in view of the variety of language distribution throughout the country. The functional importance of English, Hindi and other Indian languages varies from state to state and from person to person, and we have a "cline of bilingualism" (Kachru 1965). The English language is used mostly in urban areas rather than in the rural hinterland. Bilingual processes such as diglossia, code- mixing and code-switching are the most commonly noticed instances of code alternation. The present work focuses on these processes in the general context of bilingualism. For the purpose of survey the native speakers of Hindi were chosen. There were two main steps in the investigation. First with the help of questionnaire the interviews with 100 informants belonging to different strata of society were conducted. Secondly the speech of 20 subjects with the help of tape-recorder was recorded to ensure that the data obtained in the speech of the Hindi-English bilinguals was natural and spontaneous. An overwhelming majority of them is Hindu who speaks Hindi as L1. For the convenience of analysis and discussion the sociolinguistic constructs, the concepts of "recurrent domains" (Pride1971) and "situations" (Firth 1957) were employed. The questionnaire also sought information regarding the speakers' socio-cultural profile, such as their linguistic background, status, age, sex, medium of instruction and attitude to English, with a view to finding out correlations between these and the subjects' language use. Each of the language used by a speaker is associated with certain activities or social roles and varies with the change in topic, context, and role relations of the participants. (Contains 4 tables and 4 figures.)