The details of the Bassa Vah script's invention and development are debated. What is known is that the initial attempt to encode the Bassa language - a syllabary invented by William Crocker in the 1830s - was abandoned in favour of the Latin script. Almost a century later, a Liberian chemist, Dr Thomas Flo Narvin Lewis (also known as Dr Flo Darvin Lewis, Dr Thomas Flo David Gbianvoodoh Jidah Lewis, or Dr Thomas Gbianvoodeh Lewis), went to America to study at Syracuse University. He returned to Liberia in 1910 and began teaching the Bassa Vah alphabet, unrelated to Crocker's syllabary, to other Bassa speakers.

The controversy concerns whether Lewis invented or was taught the script, and, if he was taught it, by whom. Dalby estimates that Lewis himself invented the script in the 1920s, after his return to Liberia. However, he also records a widely accepted account by Dr. Abba G. Karnga that a Bassa man, Di Waɖa, first created the script and taught it to his lover, the wife of a chief, for which he was sold into slavery. In America, he taught it to his son, who met and taught Lewis.

Other accounts claim that Lewis learned the script while travelling in Brazil and the West Indies, from Bassa speakers displaced by the slave trade.

By almost all accounts, Dr Lewis is credited with introducing the script to Liberia. In the 1920s he commissioned a printer to print Bassa Vah texts, and enabled the script to be used in schools. Accurate reports on the scale of Bassa Vah usage are not available, and the Latin script has replaced the script in many publications, although it remains highly respected and some use is attested.
The Bassa Vah Association was established in 1959 to promote the use of the script in schools and for newspapers, books and religious books. The United Bassa Organizations in the Americas (UNIBOA) also exists for the promotion of the script.