Colvin was a significant editor of Stevenson's, preparing the Edinburgh edition of his works (1894–97); the "Vailima Letters" (1899), which Stevenson chiefly addressed to him; and the posthumous collection of "Letters" (2 volumes, London, 1900). These publications made Colvin an authority on Stevenson's life and work. He also wrote the sketch of Stevenson for the "Dictionary of National Biography" (vol. liv.), and was to have written an authoritative "Life", intended for publication simultaneously with the "Letters", but was obliged to relinquish the task to Graham Balfour.