Previous research conducted by the University of Saskatchewan demonstrated the potential to use near-infrared (NIR) spectroscopy as a nondestructive test (NDT) method. Correlations were developed between changes in NIR reflectance spectra and tensile strength after thermal aging. However, it is important to determine how NIR measurements are affected by environmental factors, such as moisture or soiling, if this method is to be used in the field. It is also important to assess the ability of NIR to predict the effects of other forms of aging, such as abrasion or ultraviolet (UV) radiation on fabric performance. In this study, the effects of soiling and moisture content on NIR reflectance measurements of protective fabrics were investigated. Changes in reflectance curves caused by soiling could be differentiated from those caused by thermal aging by examining changes to particular features in reflectance curves, rather than simply by looking at shifts in these curves. The importance of cleaning garments before NIR evaluation was also demonstrated. Results of moisture experiments suggest that the fabrics included in this study would not have to be conditioned to tightly controlled humidity levels before NIR evaluation, especially if analysis avoids wavelengths that coincide with water absorption bands. The effects of abrasion and UV radiation on reflectance curves of the fabrics considered in this study were minimal, especially when compared with the effects of thermal aging. This may indicate that NIR spectroscopy may not be as suitable for predicting changes in tensile strength caused by these forms of aging as for predicting thermal aging. Caution is necessary, however, as effects of UV radiation on reflectance curves were shown to vary considerably for different fabrics.