Despite the important role emotions play in affecting second/foreign language (L2) learners' cognition, such as their learning processes, few empirical studies have tried to find out how emotions affect the four main skills (i.e., listening, speaking, reading, and writing). In order to fill this gap, the present study aims to investigate the impact of Emotion-Based Language Instruction (EBLI) (Pishghadam et al., 2013) on the improvement of the four main skills in L2 education. The current quantitative study used a quasi-experimental design. A sample of 75 learners of English as a foreign language were divided into experimental and control groups. Regular instruction was administered to the students in the control group, and their books received no modification or supplementary parts. For the experimental group, in contrast, some modifications or supplementary sections were added to the books based on the underpinning theory of EBLI. T-test was used to find out whether the differences between the two groups were statistically significant. The data showed that EBLI had significant effect on the improvement of the four main skills of the learners. The results highlight the significance of EBLI in providing L2 learners with emotions which lead to L2 development of learners. Considering the results, it is suggested that L2 teachers should be equipped with knowledge about this influential factor (i.e., emotions) in pre- and in-service teacher education programs. In other words, L2 teachers should be trained in such a way so that they will be able to adopt a teaching methodology which, on the one hand, decreases the detrimental effects of negative emotions and, on the other hand, increases the beneficial effects of positive emotions.