The aims of this research are to find out the typical errors of grammatical aspects in the students? narrative writing and to know the typical causes of the students? errors at the tenth grade of SMA NEGERI 15 Tangerang.The research was conducted on January25th, 2012 and January26th, 2012. The writer used the instrument of writing task students. The students were asked to make the narrative paragraph writing based on the instruction. The method was descriptive analytic method; the writer corrected the written work twice. The population of the research was 228 students of the tenth grade in SMAN 15 Tangerang and the samples were taken 20 students which have the writing based on the criteria of narrative paragraph writing. This research was non- experimental research that referred to the approach of an error analysis. The procedures of the research included to identify errors, classify the errors, and evaluate the errors. The writer used Azar?s errors identification. The types of error are singular-plural, word form, add a word, omit a word, word order, spelling, incomplete sentence, article, capitalization, word choice, punctu ation, verb tense, meaning not clear, run on sentence. The writer activities were making writing task, giving writing task, analyzing the students? error writing, and reconstructing the errors. This research is hoped can be useful to the teachers and the students in developing and practicing the English writing skill. The research findings showed that the most type of errors which the students made are add a word (15.3%), verb tense (14.2%), and word choice (13.9%) in the first up to the third place consecutively. The three least type of errors are singular plural (1.7%), article (1.7%), and meaning not clear (0.6%). For the source of errors, the first rank of sources of error is intralingual transfer (61.3%). It happens because the students have not able to use the rules and grammar of English well. The second rank is context of learning (17.3%). It happens because of the teacher itself. They are not successful in explaining the material or making them interesting. The third rank is communication strategies (13.6%). It has relation with the students? style in making a sentence, and in using the words to communicate.