Implementation intentions ("If I encounter Situation X, then I'll perform Behavior Y!") are postulated to instigate automatic action initiation. In 4 studies, the hypothesis was tested that implementation intentions lead to immediate action initiation once the specified situation is encountered, even under conditions of high cognitive load. First, individuals whose action control is known to be hampered by disruptive cognitive business, such as opiate addicts under withdrawal (Study 1) and schizophrenic patients (Study 2), benefited from forming implementation intentions. Second, the beneficial effect of implementation intentions was also found in 2 experiments with university students (Studies 3 and 4) in which cognitive load was experimentally induced by using dual task paradigms. Results of the 4 studies suggest that forming implementation intentions instigates immediate action initiation that is also efficient.