A Canadian linguist of Acadian origin,R Landry, has clearly defined two forms of bilingalism, an« additive bilingualism » which is likely to enrich the mother-language elements and on the contrary a « substractive bilingualism which weaken or impoverish the basic elements of the mother- language or the source language. Could linguistic planners use these definitions, although sketchy , in devising accurate and efficient second language learning programs? amirite?