Without any exception, Pakistani undergraduate students are bilinguals. They start learning both Urdu and English from primary level. Although Urdu is the national language of the country, English is predominantly used in top bureaucracy, judiciary and all the competitive exams. Hence, there is a need for the students to be competent in both the languages. The outburst of social media and the availability of both these languages on the social media platforms mean that people can use either of the two languages. This exploratory study aimed at exploring the language preferences of Pakistani bilingual undergraduate students, both male and female, on social media. The study was qualitative in nature and employed semi-structured interviews as research tools. The students were asked a range of questions on themes like their preferred language, script, the reasons behind preferring one language over the other, the language preference of the people in their friend lists, and the resultant communication gap, if any. The interview data was then triangulated with the Facebook posts of the same students for the sake of cross validation. The findings suggest that although there are some differences in the language preferences of male and female students, the reasons are similar. While some of the students prefer Urdu over English due to ideological reasons, others do so because they believe it will be easier for them to communicate with the friends. Meanwhile, those preferring English over Urdu report that they do so because they want to practice writing English since it is an international lingua franca and with its help they can reach out to more and more people throughout the world.