The study reported in this article investigated the use of input-based tasks with young, beginner learners of English as a second language by examining both learning outcomes (i.e. acquisition) and the interactions that resulted from implementing the tasks. The participants were 15 learners, aged six, with no experience of second language (L2) learning. The target features were 36 vocabulary items (24 nouns and 12 adjectives) and plural -s. The input-based instruction consisted of three listen-and-do tasks, which were repeated nine times over a five-week period. The analysis of the process features found that even though the tasks did not require language production, the learners contributed actively. The tasks resulted in naturalistic conversation, negotiation of meaning, and "focus on form", all of which have been claimed to facilitate acquisition. The input-based group improved significantly in both their receptive and productive knowledge of the vocabulary items and in their receptive knowledge of plural -s over time. They also outperformed a control group. The study shows that listen-and-do tasks can create contexts for the incidental acquisition of both vocabulary and grammar and are effective for implementing task-based instruction for young beginner learners. (Contains 5 tables and 3 excerpts.)