In recent years, Hamas has been analyzed eitherwithin the framework of terrorism or disregardedentirely by scholars as a social movement. Byanalyzing Hamas, this book proposes a differentconceptual framework. Hamas, as an informalinstitution, is conceptualized within terms of theinteraction between overlapping networks of socialmovements and the political opportunities foundacross Palestine. Despite recent attempts by scholarsto successfully identify Hamas by labeling theorganization as either a social movement, politicalparty, militia, or terrorist group, the resilienceof Hamas as a part of the Palestinian politicalfabric make it difficult to investigate it from newperspectives. This book examine inside Hamas from aninformal institutions’ lens. It uses the contemporaryliterature to build a model of the organizationinformal institutions, analyzing it within thecharacteristic of a social movement, structuralorganization and mobilization theories. Thus, theprinciple trait of Hamas’ informal institution isalso marked with neopartimonialism, corruption,customary law and other informal institutions.