Despite the increasing interest in noticing by second language (L2) learners during the output process, little attention has been given to child L2 learners’ noticing and output. Thus, the present study investigated what child L2 learners of different English proficiency levels noticed as they composed a text and received written corrective feedback (WCF) (error correction vs. models), and how they incorporated the noticed features into their revised texts. Data were collected from twenty-six child pairs throughout three stages (composition, comparison, and revision stages) and note-taking was employed as a means of measuring learner noticing. It was found that learners were able to initiate noticing on their own when composing texts, and that highproficiency learners tended to attend to grammatical problems more frequently than medium/low-proficiency learners. WCF played a facilitative role in leading learners to notice, and their attention to language was mediated differently by different types of WCF. Learners incorporated the noticed features into their revisions, and textual revisions were mostly lexical. Error correction (EC) triggered more grammatical revisions, while the model text helped learners to notice something beyond what they could produce on their own. These findings suggest a facilitative role for output and WCF as a means of learner noticing, and the different roles of EC and model texts.