Children learn words in a social environment. In my dissertation, I examine how caregivers' social cues facilitate young children's word learning in settings that mirror their typical, dynamic learning environments. In Chapter 1, I overview prior work examining how social cues may support word learning, focusing on possible mechanisms underlying their benefits. In Chapter 2, I investigate how social cues support children's word learning over the time course of discourse topics, as opposed to the focus on single labeling events in prior studies. In Chapter 3, I expand these findings to understand how caregivers use social cues during natural discourse at home. Finally, in Chapter 4, I explore whether neural synchrony (the alignment of neural activity) within caregiver-child interactions has the potential to explain relations between caregivers' social cues and children's word learning. Together, my findings suggest that, despite the information-density and messiness of natural learning environments, social cues reduce referential ambiguity during natural caregiver-child discourse in a way that ultimately supports children's word learning. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]