Although researchers have argued that short-term structural priming is driven by both implicit and explicit memory processes, accounts of longer-term structural priming tend to focus on implicit memory processes. We explore this claim in five experiments. In the first two experiments, we replicate the finding that stronger cumulative structural priming is observed for the prepositional object (PO) construction than for the double object (DO) construction. The next three experiments explore the possibility that explicit memory effects may contribute to cumulative priming. The results of these experiments suggest that any explicit memory effects on cumulative priming are likely to be very weak. We conclude by conducting an analysis across all 5 experiments, and find that an examination of individual participants' base rates of DO production helps to explain the circumstances under which cumulative priming for the DO and PO will be observed.