The purpose of this research is investigation into the difference of linguistic-cognitive skills in bi-lingual
students, who have difference economical-social backgrounds. Two viewpoints have been in mind while
conducting this research: First, Vigotsky's theory about general cognitive development, which is applicable in
learning language. Second, Bernstein's theory of social class and the differences of speech quality. In this
research suitable theoretical explanations being suggested so that the various effects of cognitive behaviors are
clarified in learning the second language. Moreover, learning of the second language is being discussed in its
social framework. The subjects of this research include 205 grade one students of public schools in the city of
Orumieh. The age of these kids is between six and a half years to eight and a half years. These kids native language
is either Turkish or Kurdish and are taught their lessons in Farsi language. They are selected from various social
and economical levels.