Ingroup/outgroup categorisation is a repeatedly found phenomenon. Given the long-standing caste system, the Indian societal structure provides a unique perspective on such social categorisation. The Indian caste system contains hereditarily inherited identity roles defining profession and status-based hierarchies. In this preregistered experiment, we investigate the influence of caste-based identity on cooperation using a (hypothetical) Prisoner’s Dilemma. Specifically, Indian participants (N = 685) were paired with a (hypothetical) other in a Prisoner’s Dilemma, whose last name reflected either a general caste (i.e., a “high” caste) or a backward (“lower”) caste including the scheduled caste, scheduled tribe, and other backward classes. Because participants indicated belonging to a general or a backward caste themselves, they thus played the (hypothetical) Prisoner’s Dilemma with either a member of the same or a different caste group. We did not find that the partner’s caste group membership in terms of stemming from an ingroup (same caste) or outgroup (different caste) influenced participants’ cooperation. Further, we found participants from the general caste to be more cooperative when paired with (hypothetical) backward caste others (outgroup), compared to backward caste participants when paired with (hypothetical) general caste participants (outgroup); however, this difference disappeared once controlling for other demographic characteristics.