Word learning is not limited to early childhood but rather a lifelong process. As such, it is important to investigate in what ways people’s prior knowledge can shape both their ability to acquire new words as well as how these words are encoded in memory. In this symposium, we will thus explore how different types of prior knowledge—such as people’s language background or knowledge about specific words—impact word learning across different ages and learning contexts. In Talk 1, Matilde Simonetti will explore how language switching influences word learning in bilingual adults. In this context, she will discuss how knowing one word in one language can differently impact the learning of a novel word form connected to the same meaning. In Talk 2, Megan Dailey will examine the role of orthography in second-language word learning, focusing on how and under which conditions orthographic input and knowledge shape the encoding of new phonological forms in memory. Relatedly, Talk 3 by Elena Markantonakis will address how prior linguistic knowledge impacts how precisely new words are encoded, with particular attention to the retention of orthographic details after learning. In Talk 4, Marie-Christin Flohr will explore how bilingual children use statistical and prosodic cues to identify word boundaries. She will focus on the influence of the second-language learners’ first language and individual differences in listening abilities on their word learning abilities. Finally, in Talk 5, Nicole Altvater-Mackensen will investigate first-language word learning in preschoolers during shared book reading. She will use eye-tracking to measure how attention shapes children’s learning outcomes. Together, these talks showcase new perspectives on word learning, illustrating the different ways in which prior knowledge can influence word learning in first- and second-language contexts in different age groups. The talks will illuminate the mechanisms by which prior knowledge impacts how word representations are formed in memory.