This chapter offers a critical overview of study abroad research that examines complexity and accuracy in speaking and writing as well as written fluency. We discuss the relevant literature in terms of methodologies used, variables studied, operationalization of complexity, accuracy, and written fluency, and main results obtained. Gaps found in the literature are discussed, as well as limitations and areas for methodological improvements. In addition, the chapter provides recommendations for future research incorporating theoretical and methodological trends in study abroad, including the role of affective factors among minoritized students such as heritage language learners.