The maritagium, or marriage portion, was the gift of land or rents given by a father on the occasion of his daughter's marriage. Using the evidence of the surviving charters, printed and archival, which detail the terms and conditions of this grant, in combination with those charters made by the donees or their heirs which refer to the maritagium, and other evidence such as law suits and administrative records (again printed and manuscript), my thesis examined the actual grant and enjoyment of the maritagium in England. It will be shown that the custom of the maritagium was widespread, if not universal, and penetrated all ranks of society. Furthermore maritagia seem to have been given to more than one daughter, and even, on occasion to illegitimate daughters, when the family could afford to do so. This indicates that medieval society, in this period, did not concentrate its resources in the hands of one heir but distributed land within the family, in contrast to previous work which has emphasised the growing concentration of land in the hands of the male heir. The mechanism and method of granting the portion remained remarkably similar over time, varying only in the amount of land, or rent, given as a portion. In particular the thesis examines the maritagium in relation to the lives of women; the charter and legal evidence had strongly indicated that the maritagium was accounted part of the lands of a woman. Examining the maritagia charters it was evident that the charter language changed over the period to reflect this fact, changing from a gift made from a man to a man with a woman, to a gift made to a couple. This change occurred over the course of the twelfth century but, regardless of who the donee was in the original charter, or what the language used seemed to signify, from the earliest period widows were found in control of their maritagium lands. This fact had important ramifications for the position of women within society; for those women who were not heiresses marriage gave a claim to lands which they could utilise in their widowhoods. Furthermore, and unlike dower, the maritagium resembled inherited land in that it could be permanently alienated by a widow if she so desired. These findings were reinforced by the customs to be found written in the works attributed to Glanvill and Bracton, and by the surviving law suits recorded at the eyres of medieval England. In these cases the rights of women to their maritagia were asserted by widows and reinforced by the courts. In this period the ability to own and alienate land conferred power, and the maritagium gave many women the right to lands and powers which they would otherwise have lacked. This was the case until the enactment of the statute De Donis in 1285 which barred both men and women from alienating the maritagium away from their heirs, or from preventing the reversion to the donor's heirs should they prove childless. This statute, which forms the upper date limit of my thesis, thus had a major impact on the rights of women over their property, and also on the customary arrangements made by families with regard to their lands. The maritagium was not, however, only of relevance to women. It did form an important part of the lands of women who were not heiresses, indeed the practice was linked to female inheritance customs, but during marriage the maritagium was controlled and utilised by the husband. In this way men also participated in the gift. In addition because the maritagium involved the passing of land from one family to another the maritagium enabled marriage to be used as a means of dispute settlement or alliance, political, social or economic. By making prudent marriages a family could also accumulate land near the centre of the patrimony whilst disposing of outlying land as maritagia in turn. The maritagium gift thus played a major role in medieval society.