Recent archaeological study of the architecture at the Wari site of Pikillacta provides information concerning the function of one of three basic Wari architectural forms. These buildings, called Type II niched halls, occur at both Pikillacta and Viracochapampa, the two largest known Wari provincial sites. Their function can be deduced from a variety of evidence: data from excavations and associated artifacts, analogy with earlier, contemporary, and later Andean ritual/ceremonial buildings, and representations of buildings in Wari art. Based on this analysis, the niched halls apparently served as lineage halls where both real and fictive kin came to formally worship their ancestors. It is suggested that co-option of conquered elites by adoption, and thereby establishing a set of reciprocal obligations, may have been a strategy practiced by the Wari as a principal feature of their statecraft.