This study investigated the impact of content-based language instruction (CBLI) on EFL young learners' motivated behaviours, namely attention, engagement, and eager volunteering, and classroom verbal interaction. Situational factors play vital roles in shaping language learners' motivation particularly in EFL contexts. While many private schools implement CBLI programmes in Taiwan as it has been proved elsewhere that such language programmes improve language learners' motivation and academic performance in ESL contexts, such as US and Canada, the effects CBLI might have on EFL young learners have never been investigated in Taiwan. Twenty-five six-year-old year one primary students participated in this study. Both classroom observation implementing Spada and Frohlich's [Spada, N., Frohlich, M., 1995. "COLT Communicative Orientation of Language Teaching Observation Scheme: Coding Conventions and Applications." Macquarie University, National Centre for English Language Teaching and Research, Sydney, Australia.] Communicative Orientation of Language Teaching (COLT) observation scheme and qualitative analysis of classroom video taping revealed that learners tend to participate more actively in subject-learning classes than language-input classes and have benefited from the programme in terms of eagerness to volunteer and classroom verbal output. Although the differences of the subjects' attention level and engagement between content-focused lessons and language-focused lessons were not evident, there was a dramatic improvement in both types of lessons over six weeks. (Contains 2 tables and 6 figures.)