ABSTRACT Title: The impact of using source-based writing activities on EFL secondary stage students' frequency of errors Author: Amany Salem Abdel-fattah Ahmed Arafa Supervisors:     - Prof. Mohammed Farouk Abd Elsami El-Khabiry                            - Dr. Karima Mohamed Abdul-Azeez The present study attempted to investigate the impact of using source-based writing activities on EFL secondary stage students' frequency of errors; for the purpose of identifying whether the rate of committing errors has or has not reduced after using source-based writing activities. The study, also, aimed at figuring out the most common errors committed by (70) students at the first year of the secondary stage in the academic year 2020/2021 during the first semester via analyzing types of errors found in their writings. Before the experiment, the two groups answered the pre-writing test. Then, with the experimental group, different sources were used during teaching writing, while the control group was taught using the traditional activities for writing. After (13) sessions of instruction, the same writing test was administered as a post-test in order to measure the impact of using sources on students' frequency of errors. The instrument used for this study was the participants' written paragraphs in the writing test; students were required to write different genres of paragraphs (narrative, descriptive, expository, and argumentative) during the writing test. The paragraphs were collected to be analyzed (total of (6) texts per student). All the errors in these texts were identified and classified into different categories. After that, a table of frequency was formed to list the number of the most repeated errors committed by the two groups (page 21). There were (9) frequent errors that EFL first-year secondary stage students committed with a high rate of frequency, namely; (1) sentence mis-ordering. (2) verb tense, (3) subject-verb agreement, (4)prepositions, (5) pronoun error, (6) spelling, (7) punctuation, (8) inaccurate expressions, (9) word choice.  The results of the post-writing-test indicated that the mean of errors frequencies in the experimental group has reduced to reach (14.69) after using source-based writing activities. Unlike the mean of error frequencies in the control group that still with a high rate of frequency (22.86). According to the reached findings, some recommendations for further research were suggested and some pedagogical implications which might assist EFL teachers during teaching writing for secondary school students were provided.   Key words: Frequency of errors/ Error analysis/ Source-based writing activities