Teaching Turkish as a foreign language gains more importance day by day. Within the process, the ability to use the four basic skills in the best way possible is closely related with teaching vocabulary. Due to this reason, the study was conducted in order to determine the vocabulary level of students at B1-B2 level in the Turkish Education as Foreign Language classes of the Turkish Application and Research Center under Mersin University. Within the scope of the study, in different weeks the students were presented with the topic titles of "1- Narrate a day where your dreams come true; 2- Describe a match of a different branch of sports you have watched; 3- Write an essay concerning your opinions on brand enthusiasm; 4- Imagine that you are an entity other than human and write down your feelings" and were asked to write essays on these. In order to be able to obtain data from the essays written by the students, the essays were transferred into computerized environment, and the word lists of each topic title were created via the software Simple Concordance 4.07. Final lists were obtained by removing the inflexional suffixes of the words included in these lists. While it was determined that a total of 3575 words were used in the essays, removing the duplicated words resulted with a total of 782 different words. Afterwards, these words were categorized according to their types. In conclusion, it was determined that the sources used in teaching Turkish to foreigners are not subjected to an evaluation in terms of active vocabulary. This conclusion was found important not only because it sets forth the original aspect of the study, but also in terms of its quality that would serve as a guide to further studies to be carried out.