Frequency-dependent selection in the English spelling system across 1000 years of history

English orthography has largely been left to evolve freely across its thousand-year history with little top-down design or reform. Yet modern English spelling has become standardized, even if its standardized spellings are sometimes internally inconsistent. The relative freedom with which English orthography has been allowed to evolve makes it an interesting test-case for exploring whether spelling standardization might arise through a process of positive frequency-dependent selection. To maximize the chance of being understood, it pays for a writer to adopt spelling variants that occur with higher frequency, leading to those forms becoming increasingly entrenched. To evaluate this possibility, we assembled a diachronic dataset of English spelling variation, SpellEng, which we make freely available. SpellEng reports on the frequency of 112,080 spelling variants (across 32,264 lemmata) over the entire history of the English language. We use this dataset along with a model of frequency-dependent selection to estimate the extent to which English standardization can be explained by such a process. Our findings suggest that the past 1000 years of English spelling have been characterized by both positive and negative frequency-dependent selection. We discuss how linguistic dynamics and external events have shaped these periods of stability and change.