A new type of party has emerged in Israel-the federated host party. It consists of political groups and former parties which have the status of factions. Formal agreements set the rules of the game; hence, heavy constraints are placed on the host party in appointments and policy. The article discusses the emergence of federated host parties and federal factions, factors of stability and unrest in the relations of host party and factions, and the withering away of factions. Factors which account for the emergence of federal factions are: persistence, differences in size of competing parties, chain reaction syndrome, countering electoral decline, crossing the lines, and secession brinkmanship. Comparative implications suggest six elements which require further study.