Asynthesisofcrustalthicknessestimateswasmaderecentlyutilizingavailablefield,geochemical,seismicity,shearwavevelocityandgravitydatainthePhilippines.TheresultsshowthatasignificantportionofthePhilippinearchipelagoisgenerallycharacterizedbycrustwithathicknessofaround25to30kilometers.However,twozones,whicharemadeupofathickercrust(from30to65km)havealsobeendelineated.TheLuzonCentralCordilleraregionischaracterizedbythickcrust.AnotherbeltofthickenedcrustisobservedintheBicol-Negros-Panay-CentralMindanaoregion.ThispaperexaminestheinterplayoftectonicandmagmaticprocessesandtheirroleinmodifyingPhilippinearccrust.Theprocesses,whichcouldaccountfortheobservedcrustalthicknesses,arepresented.Thecontributionsofmagmaticarcsascomparedtothecontributionoftheemplacementandaccretionofophiolitecomplexestocrustalthicknessarealsodiscussed.