The original Rationalist Library was founded in 1909 by the first Secretary of the Victorian Rationalist Association (VRA), Edward Martineau Higginson, to support its campaigns and promote public debate. Edward Higginson had a great ability for organisation which included developing the Rationalist Library through donations and also running the 1910 and 1913 Australian tours of Rationalist thinker, Joseph McCabe. 

In 1919, noted public speaker John Samuel Langley was appointed as Secretary of the VRA. He founded the Rationalist Journal in 1924 and became the inaugural Secretary of the Rationalist Society of Australia (RSA) upon its formation in 1926. Langley continued expanding the Rationalist Library through donations and in 1934 established it as a Lending Library and Reading Room in Melbourne's CBD.

In 1938 William Glanville Cook became Secretary of the RSA, Editor of the Rationalist Journal, and custodian of the Rationalist Library. Bill Cook's expertise in book collecting, essay writing and research lead to the next phase of development of the Rationalist Library. It was moved to Bill Cook's house in Malvern where the Rationalist Library gradually merged with his own large personal collection of books and journals becoming the key Rationalist Reference Collection in Australia. Bill Cook extended the Rationalist Library, building subject strengths around the RSA's many campaigns over the next 40 years. After his death in 1983 Bill Cook's Rationalist Collection of around 2000 items was bequeathed to the RSA and moved back to the CBD eventually becoming the Rationalist Library and Reading Room on the 3rd and 4th Floors of Commerce House in Flinders Street.

History of the Rationalist Library 1907-2003, Ralph Biddington.

In 2002, Victoria University Library agreed to accept the Rationalist Library from the Rationalist Society of Australia (RSA) as one of its research collections and house it at the Footscray Park Campus. This collection of books, journals and pamphlets is now known as the Rationalist Collection. The Collection houses a diverse range of subjects including Australian history, Australian politics, education, theology, economics, civil society, and anthropology. Works on philosophy, especially Humanism and Free Thought, are a feature of the collection. A great number of the publications come from the Rationalist Press Association based in England and also from its branches in many countries world-wide. Featured authors include Joseph McCabe and Emanuel Haldeman-Julius.

The Rationalist Society of Australia (RSA) has been influential in its involvement in educational, economic, religious and political debates in Australian society. The RSA summarises its interests in the following statement, "The Rationalist Society of Australia prefers reason to prejudice, evidence to faith; promotes secular ethics and education; and holds lectures, conferences and social activities." The RSA champions the application of reason and evidence as the basis of public policy (from their website).