Abstract The purpose of the study was to study the subject-verb agreement errors in Saudi Arabian EFL students’ writing. The study recognized that students faced various challenges and difficulties in their process of learning English as a foreign language. The challenges were evident in the various kinds of errors that they make in their writings. The study involved a sample of 47 students in the 12 th grade from the King Saud Education Complex in Riyadh. The students’ end of second-term exams in English were studied with a view of identifying the subject-verb agreement errors that were common in their writings. The findings of the research revealed that English as a Foreign Language (EFL) students in the sampled population had subject-verb agreement errors, which were attributed to various factors. For instance, lack of adequate instruction materials, outdated curriculum, poor training of teachers, and low motivation among other factors were linked to the poor grasp of subject-verb agreement among the students. This research makes significant recommendations that will guide future research on the topic. Introduction In the highly connected and globalized world of today, the ability to communicate effectively in English through speech and in writing has become highly essential as communication across cultures and languages becomes fundamental. In the process of learning any new language, four key skills are important. They include paying attention, verbal communication, comprehension, and writing. The last skill, namely writing, comes last after the mastery of the other skills. Writing is not a natural or inborn skill. Instead, it must be learned and practiced in a formal educational or instructional setting. However, while there is no doubt that English language writing competence is important, a general agreement has been held that learning how to master written English for EFL students and people who learn the language as a foreign language is very difficult. According to Tang (2012), writing is a complex process, since it involves thinking through ideas and transferring such thoughts and ideas into readable texts that others can understand with ease. In the process of learning English as a foreign language, knowledge of grammar occurs through various stages in a person’s language development process. The ability to perform various language tasks requires the knowledge of relevant and appropriate grammatical structures, which a beginner must master. In this process, one needs to only master some English grammar rules such as the subject-verb agreement and learn to apply such rules in forming sentences. A study carried out by Stapa and Izahar (2010) found that, indeed, most EFL learners have problems with subject-verb agreement. Indeed, subject-verb agreement is a widespread problem even among the Saudi EFL learners. However, despite the existing knowledge on the challenges that many EFL students face concerning a subject-verb agreement, very few studies have focused on these issues among EFL students in Saudi Arabia. Statement of the Problem The introduction has mentioned that, indeed, subject-verb agreement is a major problem that faces many EFL students. Saudi EFL learners also face the same problem. Most of their written works have evident mistakes in subject-verb agreement, as noted by the researchers who have been quoted above. Very few studies covering this problem among Saudi Arabia