Identification of the percentage of cotton in a colored cotton-Polyester (PET) fabric is very much in demand in the textile industry. This is needed for quality inspection and custom checkups. The reflectance spectra from fabrics in the NIR range 1100-2500nm contain spectral signatures which can reveal the fabric content. The reflectance spectra are measured using a hand-held NIR spectrometer and then converted into absorbance vs. wavelength plots. Varying content of cotton in a cotton-polyester blend can be identified spectrally and a calibration method can be developed. The primary validation technique for determination of cotton content is dissolving the cotton in sulfuric acid and measuring the remaining polyester. The NIR method can be validated by comparing against the results of the acid burnout method. The range between 1400-1700 nm, in particular, contains many spectral features for identification of cotton content in a blend. An accuracy of +/- 3% can be expected from NIR measurements.