This study describes an experiment that aimed to determine if performance differences exist in simultaneous interpreting by individuals with similar general cognitive abilities, but different skills specific to the task of simultaneous interpreting. Professional interpreters’ performance in simultaneous interpreting from English into Mandarin was compared to that of two groups of student interpreters, beginners and advanced. The results showed that the professional interpreters who were not different from students in their general working memory capacity outperformed student interpreters.