We report the synthesis and investigation of multiphoton absorption properties of a novel series of diphenylamino-end-capped ladder-type oligo(pphenylene)s which exhibit greatly enhanced and efficient multiphoton (from two- to five-photon) upccinverted blue photoluminescence with which the record high intrinsic three-photon absorption cross-section of 4.56 x 10(-76) cm(6) s2 in the femtosecond regime has been obtained. Exceptionally efficient two- to five-photon-excited lasing in the blue region has also been demonstrated in which the highest two-photon-excited lasing efficiency of 0.34% has been achieved.