Abstract: This study homes in on the lexical aspects of the language shedding light on the effect of pre-teaching vocabulary and collocations on writing development. It was believed that pre-teaching relevant vocabulary and collocations could be used to improve the learners` writing ability, and the researchers have assumed that learners` L2 writing can be developed over time, in response to instruction, feedback, and practice. Forty advanced students in Goldis Institute participated in the study. Two groups were randomly determined as the control and the experimental groups, each with twenty subjects. A pretest was administered to both groups to ensure the initial equivalence of the groups. After twenty sessions of instruction and five composition tests at regular intervals, the researchers found out that the students in experimental group were more successful than those in the control group who used traditional methods. As statistical analysis of the post-test compositions shows, there is significant difference between the two groups indicating that pre-teaching vocabulary and collocations can be a useful means of helping students to improve their writing quality. Results also show that the L2 writing of these students does indeed develop over time, with notable improvements in a number of features.