Scholars have only recently begun to appreciate the diverse lives of young Islamists and the progressively divergent paths of their movements--of inter, as well as intra, Islamist competition. In Morocco, two major Islamist movements dominate the political sphere. Hizb al-'Adala w'al-Tanmiya (Party of Justice and Development) is the country's first official Islamist political party and the principal opposition party in parliament, on an upward ascendance since its entry into the electoral process in 1997. The illegal and electorally excluded Jama'at al-'Adl w'al-Ihsan (Justice and Spirituality Organization) is the largest and fastest growing Islamist--and, indeed, social or political--movement in Morocco. This paper examines the divergent patterns of Islamist mobilization in modern Morocco. How do young people navigate this diverse sea of Islamist movements? Who constitutes the membership of these movements? To examine these questions, I unpack the contours of the Islamist base--the often overlooked youth who constitute the majority of these two movements. Young people navigate a fluid trail of Islamist activism in Morocco, where their membership fluctuates across organizations, within neighborhoods, blocks, and even homes. This presentation draws on extended ethnographic fieldwork among these young activists in Morocco's economic and political capitals, Casablanca and Rabat. This research contributes to emerging debates on Islamist mobilization (specifically a greater appreciation of why young people join legal and illegal Islamist movements and the relationship between the two) and casts new light on the understudied Moroccan case.