The present study aims at investigating different methodologies and standards for measuring and calculating solar reflectance and infrared emittance, the two main properties characterizing cool roofing materials. In order to achieve this goal, an interlaboratory comparison testing has been set up among several laboratories that are members of the European Cool Roofs Council. The measurement methods practiced by the labs include measurement of the reflectivity by using spectrophotometers equipped with integrating spheres and reflectometers and measurement of the emissivity using different emissometer devices and FTIR spectrometers equipped with integrating spheres. Seventeen different samples representing the range of commercially available roofing materials and covering the full range of reflectance and emittance values have been selected and tested. The results of this study provide information on the suitability of the various methods to be used for cool roof products assessment. This work could potentially lead to the adoption of a European Cool Roof Standard.