Charles Darwin was notoriously slow to publish his theory of evolution by natural selection. His reticent approach to publishing on species is generally attributed to his supposed fear of advocating the potentially controversial doctrine of transmutation. I argue, by contrast, that Darwin’s caution was the result of a specific scientific embarrassment in his past. What concerned him most about the prospect of publishing a theory of evolution was not the topic, evolution, but the general act of publishing a theoretical book. The one other time he had tried to do so, as a young man using his theory of coral reef formation to offer an ambitious account of the history of the earth and its inhabitants, the public criticism of his “speculations” drove him nearly to despair and made him unable to deliver the book he had promised. It was this experience which shaped Darwin’s authorial priorities for his next grand theory: evolution by natural selection. He stopped thinking of his private speculations on species as an exhilarating distraction from the challenge of writing a geological book and began to plot a conservative course designed to insulate him (and eventually his species theory itself) from charges of rash speculation. I thus show that Darwin’s well-known authorial decisions on the way to publishing On the Origin of Species were made as attempts to avoid repeating, and ideally to compensate for, the missteps he believed he had made as a young author. In doing so, I argue that the geologist Charles Lyell played the key role in initially teaching Darwin how to cultivate audiences for his work (and suit work to particular audiences), but that Darwin’s eventual course constituted a partial rejection of Lyell’s approach to self-fashioning as a theoretical author.