Am ethod is presented for the initiation of freeradical and free-radical-promoted cationic photopolymerizations by in-source lighting in the near-infrared (NIR) region using upconverting glass (UCG). This approach utilizes laser irradiation of UCG at 975 nm in the presence of fluorescein (FL) and pentamethyldiethylene triamine (PMDETA). FL excited by light emitted from the UCG undergoes electron-transfer reactions with PMDETAt of orm free radicals capable of initiating polymerization of methyl methacrylate.T oe xecute the corresponding free-radical-promoted cationic polymerization of cyclohexene oxide,i sobutyl vinyl ether,and N-vinyl carbazole,itwas necessary to use FL, dimethyl aniline (DMA), and diphenyliodonium hexafluorophosphate as sensitizer,c oinitiator,a nd oxidant, respectively. Iodonium ions promptly oxidize DMA radicals formed to the corresponding cations.T hus,c ationic polymerization with efficiency comparable to the conventional irradiation source was achieved.