The basic contribution that William Lloyd Garrison made to the abolitionist movement was that he was the most outspoken abolitionist of the entire movement. His outspokenness found an outlet through the abolitionist newspaper, The Liberator, that he published.
William Lloyd Garrison was the main proponent of the idea of immediate and uncompensated emancipation. He believed that slavery was a thoroughly immoral institution and he felt that it should be abolished at once. Garrison was able to provide a voice for himself and for other abolitionists because he was the founder of The Liberator. He founded the newspaper in 1831 and used it to promote his point of view.
Thus, Garrison’s major contribution was to provide a way for abolitionists to get their views out and to strongly promote the idea of abolition himself.