Word learning is a complex phenomenon because it is tied to many different behaviors. It also involves many different perceptual and conceptual systems and is extended in time. Although complex, achieving a richer understanding of early word learning is a fundamental goal given that vocabulary development is correlated with later cognitive functioning and with processes that have a pervasive impact on general cognitive abilities such as executive function. Moreover, deficits in early word learning have a profound effect on cognitive functioning in atypical populations including children with specific language impairment. Given the complexity of word learning, a central challenge has been to establish empirical paradigms that effectively reveal the processes of word learning and to develop new theories that uncover the mechanisms that move word learning forward. Our previous work suggests word learning occurs in a cascade of individual decisions about word meaning in the moment. These decisions build on each other to shape subsequent decisions and, over multiple timescales, create developmental change. The goal of this grant is to develop and test a unified model of word learning that captures processes at both the second-to-second and developmental timescales and provides a process-based account of how individual behaviors accumulate to create development. The research plan builds and tests this model. Specific Aim 1 creates a unified model of word learning behaviors that extends beyond our prior work on noun generalization to include processes of comprehension, production, referent selection, and generalization from multiple exemplars. Specific Aim 2 adds a more complete account of object-word interactions and the development of word learning biases. Specific Aim 3 adds a memory process, enabling the model to learn a lexicon over multiple timescales and develop word learning biases. The end result of this work will be models of individual developmental trajectories that integrate word learning processes over multiple timescales-a necessary step towards intervention in cases of atypical development such as SLI, or prematurity. The integration of processes over multiple timescales and at the level of individual participants is an issue few models have addressed directly. Furthermore, the model we propose brings together work on object processing in visual cognition with work on early word learning an is related to a larger program of neurally-grounded modeling work that integrates across multiple visual, spatial, motor and language systems. Thus this model will be foundational to a full understanding of the multiple systems involved in word learning and vocabulary development, and to the interaction of these processes with cognition more generally.