LDS temples are enigmatic and problematic for non-Mormons, especially for non-Mormon scholars of Mormonism. Most information about temples—their history, use, theological significance, sociological and psychological importance—is readily available from Mormon Studies scholars and even the church itself, and temples are open for public tours before dedication. On the other hand, aspects of temple ceremonies, in particular the endowment, are not released to the public, or even to Mormons who are not temple worthy. Temple-worthy participants take vows not to reveal such elements, and they have been traditionally understood as “sacred not secret”—even if Mormons functionally understand them as both, and some outsiders disrespectfully consider them neither. This presentation explores the problematics of researching LDS temples for the non-Mormon scholar of Mormonism, and in particular seeks to answer two questions: for non-Mormons such as myself who respect sacred space, what methodological difficulties arise? Are there times when a religious tradition’s sense of the sacred is off-limits for full scholarly investigation, and if so, when and why? Relevant parallels from the Church of Scientology—another American-born religious tradition that engenders similar questions and challenges to outsiders—will be considered for context.