The aim of this thesis is to make a detailed survey, based on a representative sample of words, of how Old Swedish short a followed by the consonant combinations ld and nd has developed in the different Swedish dialects, including those of Finland and Estonia, and to contribute further to earlier discussion about the course of, and conditions governing, the development of this vowel. The words studied are (in their Modern Swedish forms): fåll n. hem', gall adj. 'barren, infertile (of a cow)', hålla v. 'hold', kall adj. `cold', ollon n. `acorn, beechmast', vålla v. 'cause', ålder n. 'age'; and n. 'duck', andas v. 'breathe', band n. 'band, ribbon', blanda v. 'mix', brand n. 'firebrand, fire', grand n. 'speck of dust' etc., hand n. 'hand', land n. 'country, land for cultivation, shore' etc., rand n. `stripe, edge' and sand n. 'sand'. For each word in the corpus, a map is used to illustrate the distribution of the different vowel qualities that occur. The study shows that the development of a in the positions in question is considerably more complex than has previously been realized. For one thing, the vowel has not developed in the same way in all the words with an a followed by ld or in all those with a followed by nd. Secondly, regular differences in vowel development are found between ald words on the one hand and and words on the other. An outline survey by the author of the corresponding developments in Danish and Norwegian dialects confirms this picture. An examination of the individual words, moreover, reveals conspicuous local deviations from the expected patterns. The author believes that this wealth of variation cannot be explained solely in terms of intralinguistic factors. As a complementary approach, an attempt should be made to apply a socio-linguistic perspective to the problem.