This thesis explores theoretical guidelines of determiners and their use in the English language. It consists of two parts - in the theoretical part we have dealt with the very concept and meaning of the determiners and all aspects that help in their proper use. Since articles are the most common determiners, but for students are the most complex to understand, theoretical focus was on improving their understanding. Other studies which have investigated the use of articles have been explained too, and CNES (Croatian National Educational Standard) has been analyzed. In the research part of thesis, the results of the research conducted among the pupils of the fifth and eighth grade of Primary school Plitvice Lakes on Mukinje and Primary school Dr. Jure Turić in Gospić are presented and analyzed. The aim of the research was to determine whether eight grade students are more successful in using articles and if they make less errors in the use of other determiners compared to fifth grade students. The results of the research have shown that eight grade students are more successful in the use of articles and other determiners compared to fifth grade students.