The tensile behavior of Nicalon fiber-reinforced silicon carbide matrix composites (Nicalon/SiC) was investigated with the aid of nondestructive evaluation (NDE) techniques. The NDE techniques include ultrasonic testing (UT), X-ray computed tomography (CT), and infrared (IR) thermography. Before mechanical testing, UT C-scans were developed to investigate defect distributions and to detect variations in the internal flaws. X-ray CT was used to characterize the type of defects and the location of flaws in composites to compare with UT C-scan results. The IR thermography was employed to monitor temperature evolution during tensile testing. This article also investigated the feasibility of using multiple NDE techniques as a means of assessing integrity for Nicalon/SiC composites. Microstructural characterization was performed using scanning electron microscopy (SEM) to investigate failure mechanisms of Nicalon/SiC composites, and the results were compared with NDE data.