This study examines the extent to which 70 Kuwaiti EFL learners are aware of the formation rules of tag questions in English. It also investigates whether the English proficiency level of the participants contributes to their correct answers on the test. For this purpose, the researchers used a multiple-choice test to measure the participants' awareness of the correct form of tag questions. The results show that Kuwaiti EFL learners are not aware of the syntax of tag questions in English (total mean = 47%). The results also reveal that the English proficiency level of the participants plays an important role in their correct answers on the test; there are statistically significant differences between the results of the Advanced Learners (ALs) and the Intermediate Learners (ILs). The researchers note that the participants encounter difficulties with certain types of tag questions, especially irregular canonical tag questions. The difficulties are ascribed to many reasons such as over generalization of the formation rule, partial application of the formation rule, lack of subject-agreement, wrong verb form and misconception of the polarity rule. Essentially, the non-existence of tag questions in the participants' first language i.e. Arabic may be the most prominent reason for the participants' inability to provide accurate answers on the test. The study concludes with some pedagogical implications that may assist teachers of English as a second/foreign language to highlight the correct use of tag questions in English in the classroom.