Structural priming (or syntactic priming) is a speaker's tendency to reuse the same structural pattern as one that was previously encountered (Bock, 1986). This study investigated (a) whether the implicit learning processes involved in long-lag structural priming lead to differential second language (L2) improvement in producing two structural types (complex, double-object dative and simple, separated phrasal-verb structures) compared to more explicit memory processes involved in no-lag structural priming and (b) whether additional explicit instruction leads to increased production of target structures than either implicit learning or explicit memory processes alone. Learners showed an overall increase in target structure production in a picture description task and marginal improvement in grammaticality judgment tests after the structural priming session. Results revealed that explicit instruction combined with structural priming speeded short-term improvement more than implicit instruction involving implicit learning alone in the form of long-lag structural priming. However, only implicit learning via long-lag structural priming resulted in increased production of the complex structure during a second testing session 1 day later. This study is the first to directly compare explicit instruction to implicit instruction in a structural priming paradigm, taking into account both the complexity of structures and the long-term effects of instruction on L2 production. (Contains 3 figures, 4 tables, and 9 notes.)