The article examined the impact of internal migration on the first language (L1) of immigrants in selected new settlements. The study adopted classic assimilation theory as the theoretical framework, while cross sectional research design was utilized for the study. The findings showed that there was first language (L1) loss among the immigrants in the new settlements as depicted by most immigrants significantly experiencing difficulties in writing and readability of their native languages (L1) when written in books among other diminishing effects of native language morphology. Finding also revealed that speaking of new dialects as language coping strategy ranging from pidginization and koineization by the immigrants in the new settlements due to diversity in the first languages (L1) were commonly used. The paper therefore concluded that internal migration results to first language loss especially in the area of first language lexicon and grammatical structure. In view of the findings, to cushion the effects of this socio-demographic phenomenon on native language, efforts to incorporate the study of local languages in basic education curriculum as well as facilitating programmes that will encourage the use of local languages among immigrants of the same streams should be advocated.
Keywords: First language attrition, Internal migration, New settlements