This thesis examines the naming-practice - particularly that of first-names - among men and women in the earliest tax registers of the 1540's from the northernmost Swedish provinces of Västerbotten and Österbotten. The aim of the thesis is first and foremost to describe, and to some extent explain, the naming-practice of the permanent population, with particular reference to the similarities and differences between the two provinces as far as personal names are concerned, and to their frequency and distribution. It has not, however, been considered possible to any great extent to compare quantitatively naming-practice in first-names with that of names in patronymics. Attention is also paid to contemporary naming-practice in, surrounding areas, especially the northern Lappmarks, and to the names of certain merchants from distant parts who were listed in the Bothnian accounts from the 1540's. The number of listed male first-names is 103 in Västerbotten in 1543 and 72 in Österbotten in 1548. Altogether, these names are borne by 2,217 and 2,787 taxpayers respectively. There was, therefore, a greater variety in naming-practice in Västerbotten, which is chiefly due to the fact that the province had more names of Scandinavian origin. The commonest first-names in Västerbotten are, in order of frequency: Olof,, Jon, Nils, Per, Anders, Lars, and Erik. The corresponding list för Österbotten is: Olof, Jöns, Lars, Per, Anders, Henrik, and Erik. The other male names are generally Scandinavian, and to a lesser extent German. Somewhat surprisingly, the Bothnian sources of this period only list the odd Finnish first-name. In the Västerbotten sources a number of men are listed only by their first-names (names without to-names). Their names were usually rare in the province. This is probably the most important reason why the patronymic is not added as a distinguishing feature at registration. Another rather remarkable method of naming according to the primary sources is what is called here the iterative name. This term refers to names which are both the first-name and the name in the patronymic, e.g. Nils Nilsson. Iterative names are found especially in the outlying areas of a parish. The choice of names there was smaller than in the central and more populous parts of the parishes. There was a strong possibility that a son would in this way happen to have the same name as his father. The investigation of female naming-pratice is based on only 110 names from each of the provinces. The commonest female names both in Västerbotten and Österbotten are, in order of frequency: Margareta, Kerstin (Kristina), Birgitta, Karin (Katarina), and Elin (Helena). Naming-practice in Kemi Lappmark was very heterogenerous, with elements of Finnish, Lapp, church, and Scandinavian names. In Torne lappmark at this time naming-practice was generally the same as on the Gulf of Bothnia. The naming-practice of the merchants was more varied than that of the Bothnian peasantry. An especially noteworthy feature is the occurrence of names of Russian merchants. / digitalisering@umu