The goal of this research is to investigate if the acquisition of L2 Spanish object clitics by L1 English learners resembles the process of diachronic change whereby these pronouns became object agreement markers. The Grammar Competition Hypothesis (Kroch 1994) is evaluated as a potential explanation to account for optionality and gradual parametric change in L2 grammars. The results show that L2 learners converge very early on the properties of clitics in L2 Spanish, although they tend to accept constructions that do not belong to the L1 nor the L2 but are attested in a previous stage of diachronic development.