Recent findings indicate that it might be necessary to integrate data from several approaches to reveal the neural mechanisms of interval timing. The evidence supports the idea that there are two timing circuits that can be dissociated: an automatic timing system that works in the millisecond range, which is used in discrete-event (discontinuous) timing and involves the cerebellum; and a continuous-event, cognitively controlled timing system that requires attention and involves the basal ganglia and related cortical structures. Because these two timing systems work in parallel, suitable experimental controls might be required to engage (and reveal) each system independently of the other.