This study investigated the interaction of bilingualism on mechanical accuracy in essay writing among Igbo learners of English in senior secondary schools in Abia State, Nigeria. One research question and one null hypothesis were raised to guide the study. The descriptive survey research design was adopted for the research and the population of the study comprised all the SS3 students of the 17 local government areas in Abia State. The sample of the study consisted of 240 students selected through multistage t-test was used to test the null hypothesis at 0.05 level of significance. The findings of the study revealed that Engligbo had interaction on mechanical accuracy in essay writing among SS3 students in private and public schools in Abia State; and Engligbo had more interaction on mechanical accuracy in essay writing among SS3 students in private schools than public schools in Abia State. Based on the findings, it was recommended among others that Teachers of English Language should be keen in identifying spelling errors of students in their essay writing. These errors should be corrected contextually in order to sustain the ideas of the essay. They should also endeavour to use the corrected words in sentence patterning in order expose students to multiple patterns in sentence construction.
Keywords: Essay Writing, Igbo learners of English, bilingualism, mechanical accuracy
