Mark Twain is still widely known for his novels The Adventures of Tom Sawyer (1876) and Adventures of Huckleberry Finn (1884), but no longer for his writing about science and technology. Yet, Twain’s interest in science and technology, and particularly scientific and technological innovation, was woven into much of his fictional and non-fictional writing throughout his life. Furthermore, not only was Twain an enthusiastic advocate of science and technology, but he was also an enthusiastic advocate of clarity, consistency and conciseness in writing and his writing advice remains timely and relevant to modern writers about science and technology. This paper brings together some of this writing advice and shows its continuing relevance and importance to scientific and technical writers in the twenty-first century.