The relative proportion of the number of kivas to secular houses varies in Cliff Palace and Spruce-tree House. In the former there are about 7 secular rooms to every kiva; in the latter about 15. Long House has a still more marked difference, there being here only a few secular houses and a maximum number of kivas. Whether this variation has any meaning it is impossible to say definitely; theoretically, as compared with modern pueblos, the proportionately larger number of kivas points to a sociological condition in Cliff Palace characteristic of more primitive times. The larger the number of kivas relatively to secular rooms the older the ruin. Long House would be regarded as older than Cliff Palace, and Cliff Palace older than Spruce-tree House, Balcony House being the most modern and the last of the four to be deserted. A cliff-dwelling with a kiva but without secular rooms is rare, and one with secular rooms but without kivas is likewise unusual. Where the latter exists it is so situated as to indicate that it was subordinated to neighboring large cliff-dwellings. The relative number of circular kivas in ruins and in modern inhabited pueblos where the circular form of room is found is larger in the ruins than in the inhabited pueblos. The proportionate number of circular rooms to secular rooms in cliff-dwellings of the Mesa Verde is also larger than in pueblo ruins like those of the Chaco. Apparently the older the pueblo the greater the relative number of kivas. If, as is suspected, a larger number of kivas indicates relatively greater age, the explanation may be sought in the amalgamation of clans and the development of religious fraternities. Hypothetically, in early days each clan had its own men's room, or kiva, but when clans were united by marriage and secret ceremonies were no longer limited to individual clans, the participants belonging to several clans, a religious fraternity was developed and several clan kivas consolidated or were enlarged into fraternity kivas such as we find among the Hopi and other Pueblos. From a study of kivas the conclusion is that Spruce-tree House is more modern than Cliff Palace. This conclusion is borne out also by the fact that the water supply at Spruce-tree House is more abundant than that at Cliff Palace.