Executive functioning (EF) is defined as a set of top-down processes used in reasoning, forming goals, planning, concentrating, and inhibition. It is widely believed that these processes are critical to self-control and, therefore, that performance on behavioral task measures of EF should be associated with individual differences in everyday life outcomes. The purpose of the present study was to test this core assumption, focusing on the EF facet of inhibition. A sample of 463 undergraduates completed five laboratory inhibition tasks, along with three self-report measures of self-control and 28 self-report measures of life outcomes. Results showed that although most of the life outcome measures were associated with self-reported self-control, only one of the outcomes was associated with inhibition task performance at the latent-variable level, and this association was in the unexpected direction. Furthermore, few associations were found at the individual task level. These findings challenge the criterion validity of lab-based inhibition tasks. More generally, when considered alongside the known lack of convergent validity between inhibition tasks and self-report measures of self-control, the findings cast doubt on the task's construct validity as measures of self-control processes. Potential methodological and theoretical reasons for the poor performance of laboratory-based inhibition tasks are discussed.