The study examined the spectrum of cultures, specifically the representation of source culture in rela-tion to Pakistan's national identity construction in English textbooks. Six locally developed textbooks in Pakistan were analysed qualitatively. We employed Cortazzi & Jin's categories of culture and Shahsani's taxonomy of source culture as an analytical framework to look at the contents of the textbooks. The content of each unit/lesson was thoroughly examined to reveal the representation of cultures that help form the students' national identity. The findings showed the representation of source, target, and inter-national cultures, with the representation of source culture outweighing the other two cultures. It further revealed the incorporation of source cultural values, norms, and roles that disseminate information about Pakistan, its historical and geographical perspectives, and the national and political heroes of the coun-try. The findings also highlighted Islamic teaching, beliefs, traditions, manners, ethics, morality, gender roles, and cultural heritage that contribute to the construction of Pakistan's Islam-based national identity. To sum up, the writers of the textbooks aimed to construct students' national identity by representing source culture materials in the English textbooks that also pave the way for the formation of Pakistani English.