A diffuse reflectance spectroscopy system is described which can operate in a contact and non- contact mode on powders, slurries and other diffusely scattering materials. Diffuse reflectance spectra are presented for a number of samples including common household materials. A comparison is made of the probe with a Bio-Rad diffuse reflectance accessory. Second derivative spectra are shown of a calibration mixture of polymer additives. The use of the diffuse reflectance system for non-destructive tablet hardness measurements is discussed. Sensor multiplexing for diffuse reflectance spectroscopy is reviewed.