Drawing on sociocultural theory, and multiple empirical studies conducted on the effectiveness of scaffolding on second or foreign language learning, the authors investigated the application of various forms of scaffolding (i.e., teacher versus peer-scaffolding) on EFL learners' incidental vocabulary learning and reading comprehension performance through a sociocultural perspective. To this end, 60 EFL learners out of one-hundred were selected through the administration of an Oxford Placement Test from three language institutes and divided into 3 groups (two experimental and one control group) each including 20 intermediate EFL learners. The first experimental group received teacher-scaffolding instruction, the second experimental group received peer-scaffolding instruction and the control group received traditional instruction with no scaffolding. The vocabulary and reading comprehension pre-tests were administered to the three groups. At the end of the experiment, the vocabulary and reading comprehension post-tests were administered. The descriptive statistics (mean and standard deviation) and the inferential statistics (a One-way ANOVA) were run to analyze the collected data. The results showed that both experimental groups had better performance than the control group and there was a significant difference between teacher-scaffolding and peer-scaffolding in both vocabulary knowledge and reading comprehension performance and the peer-scaffolding group had a better performance than the teacher-scaffolding group. This research provided some implications about different types of scaffolding for language teachers and syllabus designers.