Picture book reading is widely regarded as an activity that promotes multiple aspects of children's language acquisition, including their vocabulary development. Historically, researchers interested in what underlies the link between picture book reading and vocabulary development have investigated a suite of caregiver behaviors during picture book reading that might support learning. More recently, with the advent of modern text analytic tools, researchers have begun to look at the properties of the picture books themselves and have revealed many ways in which the language in picture book text may support learning. The current study adds to this growing literature but focuses not only on how the language in picture books might support word learning but also on how its visual content supports learning. In an adaptation of the Human Simulation Paradigm applied to commonly read picture books to English-learning children, the current study involved adults (N = 96). Results showed that a word's linguistic and visual contexts in picture books are both valuable sources of information about that word's meaning, and that their relative contributions may vary as a function of the book's target audience and the word in question. Moreover, the combined visuo-linguistic context may be an especially valuable source of information for word learning. The implications of this work for the mechanisms by which picture books contribute to word learning are discussed.