Islamist movements, including many variants of the Salafi movement, are widely understood as male-dominated spheres of action and influence. This study identifies female preachers whose writings are disseminated via a Salafi-oriented website (saaid.net) alongside the writing of their male counterparts. By comparing the writing, biographies, and profiles of male and female religious authorities, I answer several questions: (1) How is the authority of female preachers constructed, either by themselves or others, and does it differ from the construction of male authority? (2) On which topics can women be authoritative? (3) Why does a Salafi website promote female preachers when Salafi ideology appears uncomfortable with female religious authority? I answer these questions by collecting all of the writings for every preacher, male and female, on the Salafi-oriented website saaid.net, resulting in a rich data set of 21,157 texts, containing 128,000,000 words by 173 men and 41 women. Additionally, I collect professional biographies and CVs for each of these preachers, when available. Examining these data, I find that female preachers have circumscribed religious authority --- they write primarily on a limited set of topics relating to family law, culture, and educating youth, while men write on all subjects related to Islamic law. Male Salafi preachers derive authority overwhelmingly from manipulation of authoritative textual sources, primarily the Quran and Hadith. Fully 3 percent of text by men is devoted to the word "Allah,'' used primarily when invoking Quranic passages or the sayings of the prophet. In contrast, women rely on these sources much less heavily (to a degree that is statistically significant) and instead derive authority from their identities as women. The specific issues where women speak authoritatively include decrying abortion and opposing the United Nations Convention on the Elimination of Discrimination Against Women (CEDAW). This suggests that the Salafi movement permits these female preachers circumscribed authority because as women, they are able to deliver ideologically useful messages that male preachers cannot.