Originally thought to be sweat baths (estufas) by the Spaniards, kivas have been defined by archaeologists as pueblo structures specially constructed for ceremonial purposes. The actual use of prehistoric kivas is rarely discussed by archaeologists because prehistoric evidence of ceremonial or ritual activity is perceived as uninterpretable or uncommon. As a consequence, archaeological classifications of kivas are based largely on architectural form, rather than on interior features. Based on changes in architectural form, kivas do not appear in the archaeological record until Pueblo II or III. However, an examination of Pueblo I pit structures reveals that ritual features commonly associated with historically documented kivas can be identified in certain pit structures that date to A.D. 850-880. The distribution of these ritual features may offer as much or more information about the use of Anasazi ceremonial structures as pit structure size, shape, or construction.