This chapter investigates a long-standing puzzle in the economic history of the Middle East and North Africa (MENA) region: why do MENA’s native non-Muslim minorities have better socioeconomic (SES) outcomes than the Muslim majority, both historically and today? Focusing on the case of Coptic Christians in Egypt, the largest non-Muslim minority in absolute number in the region, and employing a wide range of novel archival data sources, the chapter argues that Copts’ superior SES can be explained neither by Islam’s negative impact on Muslims’ SES (where Islam is defined as a set of beliefs or institutions) nor by colonization’s preferential treatment of Copts. Instead, the chapter traces the phenomenon to self-selection on SES during Egypt’s historical conversion from Coptic Christianity to Islam in the aftermath of the Arab Conquest of the then-Coptic Egypt in 641 CE. The argument is that the regressivity-in-income of the poll tax on non-Muslims (initially all Egyptians) that was imposed continuously from 641 to 1856 led to the shrinkage of (non-convert) Copts into a better-off minority. The Coptic-Muslim SES gap then persisted due to group restrictions on access to white-collar and artisanal skills. The chapter opens new areas of research on non-Muslim minorities in the MENA region and beyond.