The Effects of the Interaction between Monomodal and Multimodal Texts on Language Performance in Pakistani ESL Context: A Longitudinal Case Study The study is about the language performance of undergraduate learners including the possibilities and challenges faced by them in the learning and development of linguistic competence, mainly communicative competence. The research examines the use of visual texts as supplementary teaching materials and their influence on the barriers caused by the learners' Affective and Cognitive domains. For these pupils, after leaning the target language for 6-12 year, insufficient communicative competence remains to be one of the major reasons for their low performance in academic and non-academic settings. It is a longitudinal Case study that challenges the hegemony of the application of the monomodal teaching materials. The study focused on 41 learners for duration of a semester during their Bachelor of Electrical Engineering at Air University, Islamabad. However, the research is conducted in two phases; the cross-sectional study in phase-I serves to provide the background knowledge of the problem being address in the second phase of Longitudinal Case study. The data collected during both phases of the study covered varieties of texts and were analyzed through qualitative and quantitative methods, thus resulting in thick description demonstrating both the process and the product of language learning. The results of both case studies reflect learners' acquisition of the second language being heavily influenced by the factors investigated and suggest a significant role for visual texts in the curriculum to minimize them.