The use of microworld simulators in classrooms and in experimental research has grown rapidly in recent years. Advocates suggest microworlds enhance learning compared with traditional instructional materials alone. However, people often have difficulty understanding the dynamics of microworld simulations, and learning and performance on microworlds typically plateau far below even simple behavioral benchmarks. Research from organization psychology suggests that assigning specific goals improves task learning and performance. This paper reports the results of two laboratory studies that examine the effects of two types of goals and two levels of goal difficulty on performance outcomes in the widely used People Express Microworld. We find that challenging compared with moderate learning goals result in higher performance outcomes. In contrast, there is no difference in performance outcomes between challenging and moderate performance goals. The findings show that including challenging learning goals in microworld instructional materials in classrooms and in experimental research will increase performance.