Teacher scaffolding plays a crucial role in shaping the quality of classroom learning, yet little is known about the effective features of scaffolding in classes using content language integrated learning (CLIL), especially in terms of its effects on learners' language and cognitive development. To address this issue, the study adopts a classroom discourse analysis approach to capture features of effective teacher scaffolding in a CLIL-framed intensive reading class. Results showed a perceived increase in learners' language and cognitive abilities while also revealing a series of effective teacher scaffolding strategies in CLIL. These include frequent use of dialogic inquiry and incidental feedback in discourse extensions, and the variation of teacher scaffolding strategies in response to students' learning needs. The findings will inform the development of the CLIL pedagogy in EFL (English as a foreign language) education in China and other parts of the world.