Marisa Casillas is interested in exploring how cognitive and social processes shape the ways in which we learn, perceive, and produce language. Her primary research examines the relationship between communicative skills and linguistic processing in children and adults. Casillas uses a combination of experimental- and observation-based methods to comparatively investigate these processes in both urban Western contexts and rural Indigenous contexts. Much of her work focuses in particular on how communicative and linguistic skills co-develop during the first few years of life, with the hope of better understanding how our capacity to produce, understand, and transmit language across generations is shaped by interactive needs.