This thesis examines transformations in burial and commemorative practices during the late Viking Age and early Middle Ages based on early Christian grave monuments (in sw. often named Eskilstunakistor); the first examples of churchyard memorials known in south central Sweden. The designs of these monuments range from stone cists consisting of five slabs - one lid, two sides and two gables - which stood above ground, to simpler constructions such as recumbent slabs with or without head- and foot-stones. Early Christian grave monuments share several characteristics with runestones, including the commemorative formula of the runic inscription as well as ornamentation in Ringerike or Urnes style. An important premise of the study is that they constitute an integral part of the late Viking Age runestone tradition. Sune Lindqvist’s 1915 dissertation gave the first systematic survey of the early Christian grave monuments; however the material has not been the subject of a new compilation since then. The thesis therefore comprises a complete overview of the material, which is presented in a separate catalogue volume. The thesis analyses the temporal, regional and contextual background of the early Christian grave monuments in order to understand the emergence of Christian cemeteries and a new religious and socio-political landscape in the transition between the Viking Age and the medieval period. This objective is divided into two levels that correspond with the two main analytical chapters. The first explores the chronology of the early Christian grave monuments, their relationship to the raising of runestones, as well as to changes in late Viking Age burial customs. The second concerns the actual sites where early Christian grave monuments were once erected. The social context of these places, as well as their significance for the emerging ecclesiastical organisation, is investigated using archaeological material contemporary with the grave monuments. The results show that early Christian grave monuments are found in areas with an early runestone period, where swift and profound changes in burial traditions take place resulting in a uniform Christian practice, together with an early church formation. It is argued that both secular and ecclesiastical authority was required to impose and maintain these major transformations. The analyses of the church sites with early Christian grave monuments, as well as of the monuments themselves, demonstrate the presence of such a social strata. Moreover, it is concluded that the basis of the ecclesiastical landscape was established from the early eleventh century. Finally the conclusions of the thesis and their implications for the understanding of the runestone tradition and its relation to the Christianisation process are discussed. The varying designs of rune-carved monuments signify substantial differences in the Christianisation process: in the way burial and commemoration was practiced during the eleventh century, whether Christian life was centrally controlled, or more decentralized with opportunities for personal choices and practices. It is argued that the diversity within the runestone tradition demonstrates differences in the early ecclesiastical organisation and provides insight into how the Christianisation process was related to social and political structures. Avhandlingen består av två band. Del I: Under runristad häll. Tidigkristna gravmonument i 1000-talets Sverige. Del II: Under runristad häll. Katalog över tidigkristna gravmonument.