In recent years there has been increasing academic interest in Islamism in the Middle East, not least in Palestinian Islamism championed by groups such as Hamas and Islamic Jihad, which are waging a bloody war of attrition against the Israeli occupation of the West Bank and Gaza. There has been less concern with Islamism among the Palestinian refugees dispersed in Middle Eastern countries such as Syria, Jordan and Lebanon. The paper outlines the sources of Islamism ("political Islam") among Palestinian refugees in Lebanon. The rise of Islamism is a complex mix of contingent factors that is fuelled by social and political deprivation and shaped by divergent views on Palestinian nationalism (secular vs. Islamist), the Islamist revival in Lebanon and "strategic localisation" that turns refugee camps into battlefields between Palestinian factions. The Islamist groups cater for narrowly defined segments of the refugee population and have been unable to attract wider support. Instead, they cater for minor, camp-based constituencies which compete with secular groups for internal control of the camps and, by implication, of the Palestinian nationalist cause itself.