With the increasing need to learn languages as a result of globalization there is a great demand on the part of the learners to communicate in a second/foreign language, which is also supported downwards by the governments and upwards by the parents. Among the many aspects of foreign language learning, affective factors are researched a lot as they are dependent on contexts, individual differences, cultural background, teaching methodology, etc., which cause a variation in the results. The current research focuses on test anxiety as one of the major affective factors. Thus it aims to identify the level of test anxiety and its relationship with gender, grade level, and academic achievement. Moreover, the causes of test anxiety were investigated according to students' own perceptions. A test anxiety scale and semi-structured interviews were conducted to gather the qualitative and quantitative data. The overall results showed that the participants had a moderate level of test anxiety. Females were found to be more anxious than males only in some aspects; low achievement scores provoked test anxiety with regard to a few items, and 9th graders were found to be more anxious than the 10th graders. According to participants' own perceptions, test validity, time limit, teacher attitudes, test techniques, proctors, length of the test, testing environment and clarity of test instructions were the causes of test anxiety.