We　report　herein　a　first-principles　investigation　on　electronic　properties　and　4f→5d　transitions　of　Ce3+　substituted　at　La3+　and　Ca2+　sites　of　La2CaB10O19　(LCB)　crystal,　using　the　hybrid　density　functional　theory　(DFT)　and　the　wave　function-based　embedded　cluster　calculations,　respectively.　The　hybrid　DFT　with　PBE0　functional　yields　a　band　gap　of　8.1　eV　for　LCB,　in　good　agreement　with　the　experimentally　estimated　value　of　∼8.3　eV.　The　energy　gaps　between　the　occupied　Ce3+　4f　states　and　the　valence　band　maximum　of　the　host　are　predicted　to　be　1.93　±　0.12　eV,　with　a　slight　dependence　on　the　local　environment.　Based　on　the　results　of　embedded　cluster　calculations　at　the　CASSCF/CASPT2　level　with　the　spin-orbit　effect,　the　experimentally　observed　excitation　bands　are　identified　in　association　with　the　two　cerium　substitutions.　The　difference　between　the　lowest　4f→5d　transition　energies　of　Ce3+　located　at　the　two　dopant　sites　are　rationalized　in　terms　of　the　variations　in　centroid　energy　and　crystal-field　splitting　of　the　5d　1　configuration　with　the　local　environment.　©　2013　American　Chemical　Society.