RESUMEN
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