This paper proposes a performance index called telepresence index for bilateral teleoperation, which can be used both for the performance evaluation of bilateral control architectures and for design purposes. This index is intended to represent a comprehensive performance objective consisting of transparency and kinematic correspondence, which are two major performance objectives of bilateral teleoperation. In order to quantify the performance objective, telepresence index has employed the error vector magnitude, which enables a seamless combination of magnitude and phase errors and the accommodation of time delay. In comparison with existing performance indices, it was observed that telepresence index possesses the comprehensiveness of performance objectives, magnitude/phase integrity, and the capacity to include time delay, which the others lack in one way or another. The index was applied to evaluate the performances of two widely known control architectures: PD-type bilateral control and Ueda's ideal control. In all cases, telepresence index has been compared favorably with the other indices in terms of clarity, convenience, and accuracy, thereby demonstrating its superiority.