The present review is a novel synthesis of research on infants' attention in two related domains-crossmodal perception and word mapping. The authors hypothesize that infant attention is malleable and shifts in real time. They review dynamic models of infant attention and provide empirical evidence for parallel trends in attention shifts from the two domains that support their hypothesis. When infants are exposed to competing auditory-visual stimuli in experiments, multiple factors cause attention to shift during infant-environment interactions. Additionally, attention shifts across nested timescales and individual variations in attention systematically explain development. They suggest future research to further elucidate the causal mechanisms that influence infants' attention dynamics, emphasizing the need to examine individual variations that index shifts over time. Child Development