Five major disasters in Pakistan affected close to 8 million people from 2005 to 2009. The 2008–09 humanitarian crisis in Khyber Pakhtunkhwa and the Federally Administered Tribal Areas (FATA) of Pakistan resulted in 2.76 million internally displaced persons (IDPs), of whom 88% were off-camp IDPs hosted by the local population. The service delivery challenges posed by the IDPs, their sparse geographical distribution and phased displacement were managed through a successful health response strategy, which focused on 13 major interventions supplemented by a set of standard guidelines for field implementation. This study evaluates the process and results attained by this coordinated health cluster strategy that has guided the mobilization and implementation of a colossal humanitarian response to an unprecedented crisis in Pakistan’s history.