The aim of the study was to determine and compare 7th, 8th, and 9th grades students' level of use and interpret the literal symbols. In addition, students' responses to questions that require use of different roles of literal symbol were examined to identify the errors. For this purpose, Chelsea Diagnostics Algebra test developed by The Concepts in Secondary Mathematics and Science (CSMS) research project was applied to total 407 students from different grade. The results of the study could be summarized in three headings : i) The majority of the 7th and 8th grade students had difficulty in using and interpreting literal symbols as generalized number, unknown and variable whereas 9th grade students had some problems particularly in understanding variable role of the literal symbols; ii) The performance of students' using and interpreting literal symbols do not increase monotonously with grade level and age; iii) Although the students' tendency of assign number value for letters, ignoring letters or considering letters as abbreviation of objects varies at different grade levels, this inclination decreased towards upper grades. However, it was revealed that when the complexity level of questions raised, upper grade level students displayed the mentioned behaviors.