The Metropolitan Museum of Art's (MMA) collection of twenty-five pre-Columbian and Colonial Peruvian wooden keros and pacchas represents one portion of an inter-museum analytical survey of these objects being undertaken by the MMA, American Museum of Natural History, the Brooklyn Museum, and the National Museum of the American Indian. Keros are important historical documents, as the materials and methods of decorating them evolved with the transition from Inka to Colonial rule in Peru. However, little attention has been paid to the technical aspects of kero manufacture. Various analytical methods including x-ray diffraction, Fourier Transform Infrared Spectroscopy, polarized light microscopy, and elemental analysis aid in the process of documenting these artistic innovations and providing a chronology for these objects.