Low-resolution spectra of UM 232 taken in 1978, 1979, and 1988 at Lick Observatory are presented. Large changes in the Si IV λ1397, C IV λ1549, and Al III λ1857 broad absorption lines are apparent. The decrease in column density in all three ions and an observed brightening of the QSO suggests that these changes are due to an increase in the ionization level driven by an increase in the central source luminosity. This mechanism has been proposed by Smith and Penston to explain small changes in the absorption spectrum of the QSO 1246-057. Our spectra of UM 232 show that the fractional decrease in optical depth is smaller at higher outflow velocities. The structure of the broad absorption-line region (BALR) is investigated by estimating an ionization parameter for each ion species as a function of velocity.