This study explored the effects of listening-based lexical focus-on-form (lexical FonF) on the acquisition and retention of morphologically complex words. One hundred eighty-two adult English learners with two levels of English proficiency (higher and lower proficiency) from a public university in mainland China were assigned to three different conditions: morphological instruction (MI), an experimental condition in which morphological instruction related to target words was provided in addition to a series of audio passages containing the target items; word meaning explanation (WME), an experimental condition in which explanations of the word meaning of target items were offered in addition to the listening activity; and one control condition (CT) in which learners were exposed only to the listening activity. The results indicated that lexical FonF led to more vocabulary gains than purely incidental FonF and that the MI condition significantly outperformed the WME condition in both the acquisition and retention of morphologically complex words. In addition, no interaction was detected between the preintervention proficiency level and word learning conditions.