Network science approaches are increasingly used in the study of human cognition. Depicting cognitive systems, such as semantic memory or the mental lexicon, as a cognitive network consisting of nodes and edges permits the application of a suite of computational and quantitative tools that allows the cognitive scientist to explicitly examine the structural properties of cognitive systems and the processes that occur in those systems. In this talk, I discuss how network science approaches can address questions related to the representation of cognitive systems and the cognitive and language-related processes that necessarily occur within those systems, with a specific focus on the structure of mental lexicon, the part of long-term memory where phonological and orthographic representations are stored, and the processes related to lexical retrieval, production, and language acquisition. Using a network science framework we will examine how process and structure interact to produce observable behavioural patterns in psycholinguistic studies, and how the structure of the mental lexicon changes over time as new lexical representations are acquired.