Contraction forms in English are mostly occur in speech and informal writing and they are generally avoided in formal writing types such as academic prose, business reports and journal articles, therefore, most teachers discourage their use in academic essays (Biber, Johansonn, Leech, Conrad and Finegan 1999). Contractions in English have two types; negative contractions (isn’t, haven’t, doesn’t) and verb contractions (I’m, they’ve, that’s). This corpus based study attempts to investigate contraction usage in learner and native English speaker essays. Major goal is to examine whether learners consider essay writing rules in respect of contractions which are accepted inappropriate for academic prose style. Five corpora, three learner and two native English, were utilized in order to analyze verb and not-contraction forms. Frequency calculations of contraction forms in each corpus compared via log-likelihood measurement for statistical significance.  Results revealed that learners use considerably more contraction forms, especially negative ones, than native English students in their argumentative essays.