Few studies examine religiosity-of-interviewer effects, despite recent expansion of surveying in the Muslim world. Using data from a nationallyrepresentative survey of 800 Moroccans conducted in 2007, this study investigates whether and why interviewer religiosity and gender affect responses to religiously-sensitive questions. Interviewer dress affects responses to four of six items, but effects are larger and more consistent for religious respondents, in support of power relations theory. Religious Moroccans provide less pious responses to secular-appearing interviewers, whom they may link to the secular state, and more religious answers to interviewers wearing hijab, in order to safeguard their reputation in a society that values piety. Interviewer traits do not affect the probability of item-missing data. Religiosity-of-interviewer effects depend on interviewer gender for questions about dress choice, a gendered issue closely related to interviewer dress. Interviewer gender and dress should be coded and controlled for to reduce bias and better understand social dynamics.