The firm was founded in 1821 by Thomas Clark,[2] then aged 22 and who had a Free Church of Scotland background.
The company was originally concerned with law and foreign literature and published under the name of "Thomas Clark".
[2] With the arrival of younger Thomas Clark (1823-1900) the firm began issuing works under the name of "T. & T.
[3] In the 1830s, it began to develop a theology list, taking a progressive evangelical stance and at times, publishing books that were not likely to make a profit.
[4] In 1965, the company began to publish Concilium, an academic journal of Roman Catholic theology.