Abingdon was one of three English parliamentary boroughs enfranchised by Queen Mary I as anomalous single-member constituencies, and held its first Parliamentary election in 1558. The borough consisted of part of two parishes in the market town of Abingdon, then the county town of Berkshire. The right to vote was exercised by all inhabitant householders paying scot and lot and not receiving alms; the highest recorded number of votes to be cast before 1832 was 253, at the general election of 1806.
Abingdon's voters seem always to have maintained their independence, and the constituency never came under the influence of a "patron" who assumed the right to choose the MP. Nevertheless, this did not always guarantee a pure election, and Porritt records that Abingdon offers the earliest case he was able to trace of a candidate trying to bribe voters with the promise of official office, later one of the most widespread abuses in English elections. In 1698, the defeated candidate, William Hucks, petitioned against the election of Sir Simon Harcourt, but during the hearing of the case it emerged that Hucks had promised that should he be elected an MP he would be made a Commissioner of the Excise, in which case he would use that power to appoint several of the voters to well-paid excise posts. The petition was dismissed and Hucks was committed to the custody of the sergeant-at-arms. (But ten years later, defeated again by Harcourt at the election of 1708, Hucks petitioned once more, on grounds of intimidation and other illegal practices, and this time Harcourt was ejected from his seat and Hucks declared to have been duly elected. Harcourt complained that the decision was a partisan one - which would have been by no means unusual at the period - "insisting to the last that he was the legal member, by a clear majority, by the most fair estimation".)
In 1831, the population of the borough was approximately 5,300, and contained 1,192 houses. This was sufficient for Abingdon to retain its MP under the Great Reform Act. (Indeed, it would have been big enough to retain two MPs had it had them, but there was no question of its representation being increased.) Its boundaries were unaltered, and under the reformed franchise 300 of the residents were qualified to vote.
In 1885 the borough constituency was abolished and the town was moved into a new county, The Northern or Abingdon Division of Berkshire. This constituency consisted of the northern part of the historic county, and as well as Abingdon included the towns of Wantage and Wallingford; it was predominantly agricultural at first, although its character changed during the 20th century with the growth of light industry round Abingdon, and it was generally a safe Conservative seat. This constituency survived essentially intact, with only minor boundary changes, until the 1983 general election, by which time it was simply called Abingdon County Constituency.
Changes in administrative boundaries during the 1970s moved most of the northern part of the historic county of Berkshire, including Abingdon, into the county of Oxfordshire. These changes were reflected in the constituency boundary changes introduced in 1983, and the Abingdon constituency was divided; most of its electors were placed in the new Wantage constituency and a significant minority including electors in the town of Abingdon were placed in the Oxford West and Abingdon constituency.
The constituency's boundaries were adjusted in 1918, and it was redefined in terms of the administrative county of Berkshire and the county districts created by the Local Government Acts of 1888 and 1894 as follows:
^Medlycott's election was declared void on petition, and a new election was held
^Southby was returned as elected by the Mayor, but on petition the Commons decided that Stonhouse and not Southby had received the most votes, and eventually declared Stonhouse duly elected
^Harcourt was initially declared elected, but on petition alleging "that Sir Simon, by menaces and by other illegal practices of himself and his agents, procured several votes for him, and several were admitted to vote for him who had no right", the result was overturned and Hucks declared to have been duly elected
^At the election of 1768, Morton was declared re-elected, but on petition the result was overturned and his opponent Bayly declared elected instead
^On petition, Mayor's election was declared void, since as High Sheriff of Berkshire he was not eligible to be elected MP for a borough within the county. A new election was ordered, by which time Mayor had completed his term as sheriff and was re-elected.