When standardized English-language tests are administered to test takers worldwide, the test-taking population could be varied on a number of personal and educational characteristics such as age, gender, first language, and academic discipline. As test tasks and test items may not always be prepared keeping this diversity of characteristics in mind, it is essential for test developers to continuously monitor their tests in terms of whether all test takers are receiving a fair test. This study investigates whether the test items on the listening section of the Certificate in Advanced English examination functioned differently for test takers from three different age groups. The main results showed that although statistical and content analyses procedures detected differential item functioning in a few items, expert judges could not clearly identify the sources of differential item functioning for the items.