Groups encounter difficulties in becoming better than their individual members. This study assesses the nature of the relationship between cognitive distance (operationalized as the extent to which the best performing individual is detached from the rest of the group) and two types of group synergy: weak cognitive synergy (collective performance is better than average individual performance) and strong cognitive synergy (collective performance exceeds the performance of the best individual in the group). We hypothesized that the relationship between cognitive distance and group cognitive synergy has an inverted U shape and we test this curvilinear relationship in two studies using judgmental and decision-making tasks. The first study shows that cognitive distance is beneficial for both weak and strong group cognitive synergy up to a point and then it becomes detrimental. A second study replicates the findings only for weak and not for strong synergy in a task that evaluates individual and collective rationality in decision making.