This dissertation deals with the long-term dynamics and fluctuations of settlements on Gotland for the period from AD 200 up until early modern times. The settlement structure on Gotland is most often described as very stable and consisting of solitary farms, established in the Iron Age. A contrasting view is presented by analyses of a vast source material from different periods. The source material consists of both physical remains, noted in the Swedish national Archaeological Sites Information System, FMIS and large scale historical maps, as well as other written sources. For the first studied period, the locations of some 2 000 houses are known, since they were constructed with sturdy stone walls and are thus preserved. The source material for the following periods is scarcer, but some hundred Viking Age sites are identified, mainly by the find places of silver hoards. By retrogressive analyses of historical maps, from the decades around the year 1700, and other written sources, later periods are analysed. All available data are gathered in geodatabases, which enables both generalised and detailed spatial and statistical analyses. The results of the analyses show a more varied picture, with great fluctuations in the number of farms; the existence of villages is also clearly indicated in a large part of the settlements. The villages are centred on kinship and the lack of strong royal power or landed gentry meant they were not fixed in cadastres, as fiscal units, as villages were on the Swedish mainland. Two peaks, followed by major dips, were identified in the number of settlements and thus in the population. The first peak occurred during the late Roman Iron Age/Migration period, which was followed by a reduction in the Vendel period of possibly up to 30-50%. After this, a recovery started in the Viking Age, which culminated during the heydays of Gotland in the High Middle Ages, with population numbers most probably not surpassed until late in history. This upward trend was broken by the diminishing trade of Gotland, the Medieval agrarian crisis, The Danish invasion and later events. All this resulted in a decline, probably as great as after the Migration period.