Jerusalem - the third holiest city in Islam - is home to some 300,000 Muslims. But due to Israel’s occupation, they live difficult and disrupted lives. What might it mean for Muslims to practice their faith - on the ground, day by day - in such a conflicted place? One way religion becomes a meaningful category in people’s lives is through ritual. Scholars of Muslim religious practice have been attuned to this insight and observed it in various contexts. But their analyses have often been predicated on an implicit and unquestioned assumption - that people who desire to perform rituals have the means to act on their intention in regular and routine ways. Scholars have also shown that when societies are in rapid transition - be they weakened or threatened - their rituals often evolve with them. In this project, therefore, I ask: what happens in Jerusalem when Muslims live under the existential threat of occupation and their ability to routinely perform religious rituals cannot be assumed? I argue that when rituals are disrupted, Muslims are forced to improvise. Religious rituals - like the performances of skilled jazz musicians - are spontaneous and dynamic but also practiced and deliberate. Rituals are spontaneous in that they respond to the occupation’s disruptions, making physical and discursive adjustments. They are practiced in that Muslims draw from an established repertoire of themes that includes Islam and sacred space, nationalism and resistance, local culture and geography. I term the coalescence of these dynamics the “improvisation thesis” and explore three case studies where specific improvisations have different levels of resonance. The Naqshbandi improvise rituals to make peace, but they are discordant with other established themes; Ramadan rituals have resonance that define specific moments; and the improvisations of the Murabitat are deeply resonant, influencing Muslim rituals throughout the city.