Although executive functions can be improved by training, little is known about the extent to which these training-related benefits can be transferred to other tasks, or whether this transfer can be modulated by the type of training. This study investigated lifespan changes in near transfer of task-switching training to structurally similar tasks and its modulation by verbal self-instructions and variable training, as well as far transfer to structurally dissimilar ‘executive’ tasks and fluid intelligence. Three age groups (8–10; 18–26; 62–76 years of age) were examined in a pretest-training-posttest design. We found near transfer of task-switching training in all age groups, especially in children and older adults. Near transfer was enhanced in adults and impaired in children when training tasks were variable. We also found substantial far transfer to other executive tasks and fluid intelligence in all age groups, pointing to the transfer of relatively general executive control abilities after training.