This paper compares definitions of Islamophobia (IP) and antisemitism (AS), using academic and lay sources. Despite the volume of work on both topics, concrete definitions are rare, as is comparison across the literatures. My overall goal is to produce coding instructions for how to recognize and classify IP and AS in speech, including texts like interview transcripts, NGO statements of purpose, or debates between students. I am producing three alternative definitions for each exclusionary discourse: narrow, mid-range and wide. For example, a wide definition of AS treats most negative speech about Israel as AS, while a narrow definition includes Israel only in limited circumstances. My larger purpose is to track how definitional patterns shape such things as: debates about Israel, perceptions about whether Jews and Israel properly align with a Christian west or a Muslim Middle East, NGO interventions into Israeli politics, and existing attempts to unite Muslims and Jews against US nativism. As an example of the latter, the ADL seeks to create bridges to US Muslims by tracking IP as well as AS. However the IP they track is essentially a wide definition of AS with the word “Muslim” substituted for “Jew”. As a result the ADL tracks violent activities like desecrating mosques, but does not incorporate the links to colonialism and colonial discourse that are central to most definitions of IP. Thus in this case, unexamined definitional assumptions impede attempts at alliance.