Luzon is the largest island group in the Philippines. There are 7 regions in Luzon. Region 1 -- the Ilocos region. CAR -- the Cordillera Administrative Region. Region 2 -- the Cagayan Valley region. Region 3 -- the Central Luzon region. Region 4 -- the Southern Tagalog region. NCR -- the National Capital Region. Region 5 -- the Bicol region.