Cogmed Working Memory Training (CWMT) is a commercial cognitive-training program designed to foster working-memory capacity. Enhanced working-memory capacity is then supposed to increase one’s overall cognitive function and academic achievement. This meta-analysis investigates the effects of CWMT on cognitive and academic outcomes. The inclusion criteria were met by 50 studies (637 effect sizes).Highly consistent near-zero effects were estimated in far-transfer measures of cognitive ability (e.g., attention and intelligence) and academic achievement (language ability and mathematics). By contrast, slightly heterogeneous small to medium effects were observed in memory tasks (i.e., near transfer). Moderator analysis showed that this effect was weaker for near-transfer measures not directly related to the trained tasks. These results highlight that while near transfer occurs regularly, far transfer is rare or, possibly, nonexistent. Transfer thus appears to be a function of the degree of overlap between trained tasks and outcome tasks.