This article reports a comparative study of first language (L1) Chinese and second language (L2) English lessons in Hong Kong secondary schools. Aiming to explore how to take advantage of L1 academic proficiency for the benefit of L2 development, the study asked how Chinese and English lessons compare in terms of the content knowledge covered and the levels and depth of such coverage. Through a corpus-aided approach, 3 differences were identified, namely, the “aboutness” of the lessons through a keyword analysis, the “abstractness” reflected in the use of metalanguage, and the “richness in coverage” of meanings in classrooms. The findings indicated that the Chinese lessons were either text-based, involving discussion of literary concepts in metalanguage, or task-based, engaging students in debating about a current issue, while English lessons were based on linguistic knowledge and composed mainly of discrete grammatical drills through simple classroom routines. This article argues that the 3 differences identified were deficiencies in the L2 classrooms. However, they could also be areas where crosslingual transfer might be possible. Constant exposure to literary text-related concepts and cognitively complex tasks in the L1 may lead to students’ development of academic language proficiency; such proficiency could be capitalized for the development of academic proficiency in the L2. Copyright © 2012 The Modern Language Journal.