In probability learning experiments, a participant is typically presented with one of two alternatives to select, one of which will lead to a reward. For example, in a 70:30 task, one alternative will lead to a reward on 70% of trials while the other will yield a reward on the remaining 30% of trials. On probability learning tasks, adults are said to “probability match,” selecting each alternative with the relative frequency with which it has been reinforced. Children, on the other hand, are said to “maximize,” always guessing whichever alternative has been reinforced more often. The different patterns between adult and child behavior are thought to have implications for language learning, especially qualitative differences in child and adult language learning skills and developmental trajectories on a range of other cognitive tasks. However, a thorough review of the literature suggests that behavioral profiles of adults and children are not as straightforward as has been claimed. Crucially, there is little empirical support for a true probability matching strategy by any participants. Differences in features of the experimental task and in meta-task knowledge contribute to variability across tasks and participants in ways that only become evident when systematically reviewing the literature. Differences in probability learning across populations may not underlie or indicate causal differences in more complex cognitive behavior, but rather may themselves be another pattern of behavior that theories of learning and development must account for.