There were two major objectives for this thesis: 1) to integrate the existing literature based on vigilance, noise, and neuromuscular fatigue and 2) to determine the effects of muscle contraction intensity, neuromuscular fatigue, and noise on the performance of complex and simple vigilance tasks. Vigilance or an individual's state of physiological or psychological readiness to mediate performance when reacting to a stimulus can be affected simultaneously by noise and neuromuscular stimuli. Noise exposure and muscle contraction have been shown to both negatively and positively affect vigilance performance. However, this contradiction may be a result of differences in muscle contraction and noise intensities, durations, and type as well as the complexity of the vigilance task. It was determined in the present experiment that continuous noise at an intensity of 95 dB (A) impairs both simple and to a greater extent complex vigilance task performance. Isometric muscle contractions at 5% and 20% of a maximum voluntary contraction also impaired simple and complex vigilance task performance. There did not seem to be an interaction effect between noise and contraction intensity.