Room 129W is an original Chacoan room of large size that measures 5.8 x 3.3 m and is located in the southeast sector of Salmon Pueblo. The room was heavily used by the Chacoans, perhaps initially as a residential room and later as a burial and trash repository. The later San Juan occupants also used the room as a trash depository. Room 129W was one of the most complex units at the site. It contained 244 defined stratigraphic units, and because of its size and complexity, excavations reached but did not complete clearing of the Chacoan floor. Its first story was constructed about 1090 and then its function shifted when an extensive internal milling bin facility was established. The Room 129W ground story was abandoned during the Chacoan occupation and became a repository for an exceedingly complex series of trash mounds. Trash deposition continued into the San Juan occupation. A San Juan floor above these trash deposits indicated a final function just before the room was totally destroyed by fire. Of the strata, more than half were structured trash deposits and were part of 19 separate trash mounds. The trash deposits were predominantly of Chacoan or mixed Chacoan–early San Juan age, with only a few dated to the later San Juan occupation. Other strata included several floor complexes, roof-fall, occupational fill, feature-related strata, and construction debris. In all, 129 features were associated with 129W. More than 50 relate to roofing and construction. Chacoan age features included five doorways, vent windows, four hearths, several milling bins, a macaw skeleton, two wall niches, and several floor pits of unknown function. San Juan features were somewhat less numerous, and beyond roofing features, they included a burial, caches, a modified doorway, and several trash mounds. Masonry indicates construction during the initial occupation, around 1090, and a long and complicate use-life of the room through the end of the Chacoan period and into the San Juan period.