Transnational Muslim NGOs are important actors in the field of development and humanitarian aid. Through micro-sociological case studies, this article provides new empirical insights on the organizational identity of some of these NGOs. Using the post 9.11. aid field as a window through which to explore transnational Muslim NGOs, the article analyzes the ways in which two of the largest Muslim NGOs Islamize aid and the kinds of Islam they construct in this process, discussing how this relates to their position in the contemporary aid field. The Saudi Arabian International Islamic Relief Organization and the British Islamic Relief serve as emblematic examples of transnational Muslim NGOs today, each presenting different ways of understanding Islam: One promotes an all-encompassing Islam, embedded in almost all aspects of the organization; while the other demonstrates a quasi-secular Islam, most often relegated to the personal sphere. Likewise, the two organizations Islamize aid in different ways, based on different interpretations of the Global War on Terror and mainstream development discourses. The article concludes that the positions of the two NGOs are best understood as poles in a continuum, stretching from an embedded Islam, encouraging a thoroughly Islamized aid and blocking integration into the field of mainstream development and humanitarian aid, to an invisible Islam, accompanied by an almost secularized aid and facilitating integration into the aid field.