This paper examines the intertwined dynamics of diasporic identity and nostalgia in the literary works of Jhumpa Lahiri, the Pulitzer Prize-winning author of Bengali-Indian descent whose fiction has become central to the canon of South Asian diasporic writing in English. Drawing on diaspora theory, postcolonial criticism, and cultural memory studies, this paper analyses Lahiri's major works — Interpreter of Maladies (1999), The Namesake (2003), Unaccustomed Earth (2008), and The Lowland (2013) — to trace the recurring thematic and formal preoccupations with belonging, cultural displacement, intergenerational conflict, and the longing for an originary home that defines the diasporic imagination. The paper argues that Lahiri's treatment of nostalgia is neither simple sentimentality nor straightforward critique; rather, she employs nostalgia as a complex affective structure through which her characters negotiate the irresolvable tensions of living between two cultures, two nations, and two selves. Her fiction illuminates the ways in which diaspora produces not a stable hyphenated identity but a condition of perpetual negotiation, grief, and reinvention.