The thermoluminescence of scheelite-structure tungstates is studied as a function of their composition. The nature of the thermoluminescence centers is elucidated. The Na'Ca-V'O complex is assumed to be responsible for the 100-K peak. The thermoluminescence at 164 and 290 K is tentatively attributed to the Na'Ca-V'O'-WO'4 complex, which may capture both electrons and holes. The temperature quenching of luminescence is considered.