This dissertation investigates linguistic variation and optionality in the Spanish clitic system of bilingual L1 P’urhépecha speakers from Michoacán, México to determine if interference from L1 features results in non-standard use of accusative and dative pronouns in L2 Spanish. Using the theoretical framework on feature/morphology mapping in bilinguals by Lardiere (2000, 2005, 2009) and Sánchez’s theories of functional interference and convergence (2003), I investigated three phenomena occurring in Spanish and Amerindian contact varieties or amongst bilingual speakers: neutralization of gender (and number) into an invariant accusative clitic lo, omission of anaphoric clitics, and liberal accusative clitic doubling. I also investigated the ...