Three methods for recording color change on paintings have been considered by the National Gallery. The first has previously been described to the ICOM Committee (1). Two others are described here: reflectance spectrophotometry and scanning colorimetry. The National Gallery is now set up for routine measurement of color using a reflectance spectrophotometer specially built for this work by Wright and Wassall at Imperial College, London. Areas about 4 mm diameter are selected for a complete reflectance curve (380760 mm). Readings will probably be repeated every 5 years. In the second method now being investigated, scanning colorimetry, the painting is scanned at three wavelengths. Reflectance readings are digitized and recorded on magnetic tape. Tapes taken 5 or more years apart will then be compared using computer programmes. Author's address: Scientific Department, The National Gallery, Trafalgar Square, London WC2N 5DN, Great Britain.