The present study explored the effect of task repetition with and without explicit instruction on EFL learners' (n = 26) explicit and implicit English regular past tense structure development. One group (REP) repeated the same task (n = 12) while another group (EI + REP) received explicit instruction between performances of the same task (n = 14). The explicit and implicit knowledge was measured before the study began, after the main, repeated and procedural task performances, and after a two-week delay by means of an untimed grammaticality judgment test and an elicited oral imitation test respectively. The results indicated the role of explicit intervention in the EI + REP group's both immediate and delayed explicit knowledge development, while the sole task repetition in the REP group developed a temporary attention to the target structure. Furthermore, the EI + REP condition led to implicit knowledge as elicited by an oral imitation test, but with a delay. Findings are discussed in light of the concepts of attention and processing capacity in second language acquisition.