An Interplay of English and Urdu Languages in Pakistani ESL Learners: Implications of Sapir-Whorf Hypothesis of Linguistic Relativity This qualitative enquiry investigates the perennial question about the relation and intersection of language and thought. Taking Sapir and Whorf's (SWH) proposed causality between a language and cognitive processes as well as their standpoints of linguistic determinism and linguistic relativity as foundational to this debate, I have taken recourse to other re-conceptualizations offered by linguists. And according to the milder versions of this hypothesis, language can influence thought in various degrees and ways, and resist the decrees of an absolute takeover of language on thought. The first two chapters establish grounds for the actual research, by systematically debating these dimensions. This research makes use of these hypotheses, re-conceptualizations to observe the interplay of English and Urdu language in Pakistani ESL learners. The effort is neither aimed at comparing and contrasting the two languages nor to observe the phenomenon of code switching/ mixing. Instead, the focus remains on tracing the patterns of communicative choices Pakistani learners make for ensuring accuracy of expression and conveyance of fuller meaning. This has been achieved by means of focus group discussions and one to one interviews with the participants. The participants were engaged in dynamic, motivational and meaningful themes, instead of stereotype speaking skills topics, with the permissible use of Urdu where necessary. The third chapter (methodology) encapsulates the methodical stances I have adopted to view manifestations of SWH, during the communicative engagements of the participants. Later, the analysis and interpretation of the voice data is carried out by means of certain communicative strategy typologies that dissect and categorize discussion content across different parameters, for precision and meaningfulness (chapter four). From the analysis it is evident that the SWH does hold sufficient grounds when its application is seen in a bilingual situation. Such a situation produces rich and diverse data and has highlighted delicate intricacies of cultural and moral contents embedded within a language which majorly shapes influences on thinking patterns of its speakers, providing insightful conclusions (chapter five) and new dimension to this co- relational activity excited by language.