In this study, a new damage detection technique is developed so that delamination in a multilayer composite plate can be detected by comparing multi-path pitch-catch Lamb wave signals in a piezoelectric transducer network rather than by comparing each signal with its corresponding baseline signal obtained from the pristine condition. The development of the proposed technique is based on the premise that the fundamental anti-symmetric mode (A0) slows down when it passes through a delamination area while the speed of the fundamental symmetric mode (S0) is invariant. First, the delay of the A0 mode in each path is used as a delamination sensitive feature and extracted using a proposed mode extraction technique. This mode extraction technique uses dual piezoelectric transducers composed of a concentric ring and circular piezoelectric transducers, and it is capable of isolating the A0 mode in any desired frequency without frequency or transducer size tuning. Once the time delays of the A0 mode are computed for all pitch-catch paths in the transducer network, an instantaneous outlier analysis is performed on these features to identify wave propagation path(s) affected by the delaminated region(s). Because the time delays of the A0 mode are instantaneously computed from existing multiple paths, it has been demonstrated that robust delamination detection can be achieved even under varying temperature conditions.© (2011) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.