We have measured the temperature sensitivity, T-0, of GaAs-(Al,Ga)As, GRINSCH, multiple quantum-well (MQW) lasers with different numbers of quantum wells ranging from one to ten. Our data suggests that there is an optimum number of wells, namely five, where T-0 is highest, Using a temperature-dependent model based on drift-diffusion equations, we have systematically analyzed the temperature sensitivity of a MQW GaAs-(Al,Ga)As laser, The T-0 versus well-number behavior observed experimentally is verified, and the important temperature-dependent factors are identified.