The aim of this paper is two-fold: (a) to investigate scaffolding strategies employed by two EFL teachers in the process of instructing more and less proficient learners, and (b) to explore the most effective strategies used by teachers with students. Two elementary school English teachers were invited to take part in this study. Both were asked to select four students, two for each pair of more and less proficient learners, plus three reading texts, one for four students and one each catering to more and less proficient learners' level. Each student took the comprehension test before and after the instruction. After instructions, each student was interviewed by the teacher in a semi-structured format. Both kinds of data were video- and audiotape recorded and transcribed verbatim by two research assistants. Teacher's instructional turns were first highlighted and relevant turns grouped together as episodes. Relevant episodes were then grouped together as a discussion theme. Four themes--offering explanation, clarifying and verifying student understanding, linking with student background knowledge, and negotiating meaning--were generated for discussion. Oral interview data yielded the most effective scaffolding strategies used by teachers with students. Pedagogical implications are suggested for class use. Interview questions and transcription key are appended. (Contains 5 tables.)