Early vocabulary development is crucial for future cognitive and academic outcomes, and parent-child booksharing has been recognized as a powerful home literacy practice to promote word learning. However, evidence about the link between booksharing and language development in diverse cultural and socioeconomic settings is currently limited, hindering the formulation of a broadly applicable framework to understand the favorable conditions for early vocabulary development. This study explores the relationship between booksharing and early receptive and expressive vocabulary in a sample of 183 mothers and their toddlers in Costa Rica, a context where reading is not a common practice and children have limited access to books. Mothers completed an interview about their booksharing practices and reported children’s receptive and expressive vocabulary. Results demonstrated a positive link between maternal booksharing and children’s expressive vocabulary. Child gender moderated the link between booksharing and receptive vocabulary, exhibiting a stronger association in girls than in boys. Mothers with lower education levels reported higher expressive vocabulary scores for their children than mothers with higher education levels. These findings underscore the significance of booksharing in the home literacy environment, even in cultural contexts with distinct reading practices. Moreover, they highlight the need to incorporate sociocultural factors into comprehensive accounts concerning the role of booksharing in early word learning.