The main aim of this study is to reveal the role of negative transfer among Hungarian learners of English. The literature review summarizes the main findings about Contrastive Analysis, the forerunner of Error Analysis. The review also highlights different types of errors, especially the role of interlingual or transfer errors in second language learning. The changing role of the mother tongue is also highlighted. The research project’s aim is to compare elementary students with pre-intermediate ones, on the basis of their age, gender, the number of years they have been learning English, their ease or difficulty at learning English. A questionnaire, a translation task and multiple choice questions were used in order to get the answers for the questions of comparison. The research ends with reviewing the results have found after totalizing data from the participants, and it explains the potential causes of these results. The study ends with a suggestion for further research in comparing developmental and transfer errors in order to give a framework and a ratio of these errors.