In the Piedra district of southwestern Colorado[106] are found [jacal] buildings in clusters of from three to fifteen. The different structures were often close, but did not touch. A number of clusters, laid in a crescent shape around a circular depression, comprised a village. These depressions are thought by some to have served as reservoirs, or possibly sometimes as plazas or dance courts. Others hold the opinion, based on the results of more recent excavations in other areas, that they may contain pit houses.[41] The earliest houses were pits with sloping jacal walls. Later the floors were merely depressed, and walls were perpendicular. This type was eventually combined with two-room storage buildings of crude masonry. Next, the jacal construction disappeared and the rooms made of masonry were enlarged and became dwellings instead of storerooms.

In the nearby region of the La Plata drainage,[95] houses in the beginning of the period differed little from those of Basketmaker times, except that they were somewhat more massive and more masonry was used. There was some [jacal] construction, but usually a variant form was employed in which only a few widely spaced wooden supports were used. Sometimes the entire wall consisted of clay pressed into position with the hands, and the posts were absent. Stones were sometimes added to the clay, and some crude [coursed masonry] has been found. Stone slabs commonly formed the wainscoting. Houses were usually grouped in a crescentic form along the north and west sides of a depression containing a subterranean chamber. No dance courts or plazas have been found.

During the latter part of Developmental-Pueblo times in the La Plata area, [jacal] and slab construction were replaced by stone and adobe, and walls became more massive. At first the adobe was considered the important mass and only a few stones were incorporated, but, as time went by, the ratio changed and stone predominated with mud serving only as a mortar. Crescent-shaped room-placement changed to a rectangular structure.

In the Ackmen-Lowry region[82] of southwestern Colorado most early Developmental-Pueblo sites consisted of one or two above-ground rooms associated with a pit house which may have served as a domicile as well as provided a place for the celebration of ceremonies. The surface structures were of slabs topped by masonry, or were of [jacal] construction. Later houses were built of [coursed masonry] and usually contained from four to six rooms. The associated pit houses seem to have been used exclusively as ceremonial chambers. Also found in this area was a good-sized Pueblo, known as Lowry Ruin, which was occupied late in Developmental-Pueblo times as well as during the succeeding period. Thirty-five rooms have been uncovered, but there is evidence that the pueblo was modified six or seven times, and it is estimated that probably no more than fifteen or eighteen rooms were occupied at any one time.

At Alkali Ridge in southeastern Utah,[7] thirteen sites have been excavated which have yielded valuable information about architectural development. Ten of these contained Developmental-Pueblo structures. In this area, even as early as the eighth century, pueblos with as many as three hundred above-ground storage and living rooms were being built in association with large and small pit houses. These pueblos consisted of long curving rows of contiguous rooms with the larger dwelling units in front of the small chambers used for storage. A variety of wall types was used, often in combination. They include upright stone slabs, [jacal], and some [coursed masonry].

During the latter half of Developmental-Pueblo times in this area there were buildings made of [jacal] with stones imbedded in the adobe. Those found range in size from one to twelve rooms, and some may have been larger. There were also structures of [coursed masonry]. Some of these contained only one or two rooms but others may have been fairly large.

In excavations near Allantown, in eastern Arizona,[112] the evolution from simple masonry granaries to multi-roomed houses, and the development from simple, partially subterranean houses to highly specialized kivas, or ceremonial buildings, is clearly shown. There the change from domiciliary pit house to unit house seems to have occurred in the period between 814 and about 1014 A. D. This, however, was a slower development than in other areas. In the Chaco Canyon area of New Mexico, for example, great communal houses, with several stories and hundreds of rooms, of which the unit-type house seems to have been the forerunner, apparently were started by 1014.

Unit houses, which were commonly built in the second part of Developmental-Pueblo times and in the following period, were above-ground structures built of stone and adobe. They were one story in height and usually contained from six to fourteen rooms. These rooms were sometimes placed in a long row, sometimes in a double tier, and, in other cases, were arranged in the shape of an “L” or rectangular “U”.

Unit houses are occasionally referred to as [clan] houses, for some archaeologists believe that they may have been occupied by single family groups. Present day social organization in the western pueblos is based on clans, and it is believed that this is of long standing and probably extends far back into prehistoric times. Descent is traced in these pueblos in the maternal line. In such villages a clan is a group made up of individuals descended from the same female ancestor. Houses belong to the women, and a family group which lives together usually consists of a woman and her daughters and their families. The husbands belong to other clans. They live with their wives’ groups, but their religious affiliations are with their own clans. The kivas, or ceremonial chambers, belong to the men of the clan and serve as club rooms as well as providing a place where secret religious rites may be performed.

In Developmental-Pueblo times, kivas were very similar in form to those used at the present time in the eastern pueblos. They were circular, subterranean structures which lay to the south or southeast of houses. Walls were of masonry, and there were encircling benches in which pilasters were often incorporated. Roofs were normally cribbed, and entrance was usually through the smoke-hole in the center; although, in some unit-type sites in southwestern Colorado, stone towers are found containing manholes which led into tunnels connecting with kivas.[83]