An important measure of the success of Rational Dissent is the extent to which its publications were sold, circulated, and read. Limited surviving evidence makes it difficult to establish with any accuracy the number of people across England who read or borrowed books written by Rational Dissenters. However, we can form a picture of the impact and nature of the appeal of Rational Dissent at the end of the eighteenth century from published lists of subscribers to Rational Dissenting works, to the Manchester and Hackney Academies, and to the London and Western Unitarian Societies. The contribution of money by these subscribers is a major indication of commitment. While those who made donations towards anti-slavery organisations or for the support of the exiled French clergy might have been encouraged by the thought of favourable publicity, such a motive cannot be attributed to subscribers to Unitarian literature and organisations. They were more likely to attract hostility, and were motivated, in large part, by theological interest.

Analysis by R. K. Webb of subscribers to the works of John Jebb and Nathaniel Lardner, and by David Wykes into benefactors of and subscribers to Manchester College, has provided valuable insights. This book takes their work further in analysing 11 subscription lists to published works, 2 lists of subscribers to academies, and 6 to regional Unitarian societies, between 1770 and 1800. The total number of subscriptions appearing in these sources reaches 6,047. The number of subscribers varies according to the focus of the subscription. There were 1,235 subscribers to the posthumously published works of Paul Henry Maty and 511 to those of Nathaniel Lardner. The Unitarians John Jebb and Edmund Butcher attracted 602 and 627 subscriptions respectively. At the other end of the scale, in 1792 the newly formed Western Unitarian Society acquired only 31 subscriptions.

The subscriptions to two works are deliberately excluded from this analysis. Robert Robinson's publications are not included since, although Priestley claimed him as a Unitarian, Robinson himself never admitted to this title, despite suggestions that he turned to non-Trinitarian opinions in later life.