Britten’s two early operas, Peter Grimes and The Rape of Lucretia, were collaborations with two very different librettists. Both were poets, but the first, Montagu Slater, was also a communist, a practised journalist, novelist, editor, and critic, a decade older than Britten, and he brought considerable scenario, playwriting, and theatrical experience to the project; the second, Ronald Duncan, also a playwright, was an anti-democratic pacifist, convinced of the power of poetic expression and of his value as a poet; he was more willing than Slater to adapt to Britten’s demands, but still had very decided ideas of his own. Britten abandoned Slater after Peter Grimes, despite its success, and The Rape of Lucretia proved the only opera he would write with Duncan. This essay provides a detailed biographical and critical outline of each writer’s work up to their collaboration with Britten, showing how their approaches to writing a libretto differed, what they contributed, and why Britten moved on to other writers for his subsequent operatic work.