Small informally organized family-owned grocery retailers—kiranas—are ubiquitous in India and have retained market dominance while facing increasing competition from large formally organized retailers (FORs). Yet, strategy literature has under-explored such informal businesses. We explore kiranas’ distinct strategic practices that give them competitive advantage over FORs, generating kiranas’ sustained market dominance. To explore kiranas’ informal strategizing, grounded theoretic analysis of our multi-year case study suggested the employment of strategy as practice (SAP) framework, enriched with the social exchange theory (SET) concepts of trust and reciprocity. We find that the kiranas’ sustained enactment of strategic practice such as free-of-charge home-delivery significantly depends on contextually rich, reciprocity-based social exchange relationships with customers which evolve through praxes involving continuous exchange of trust. The practice enactment and exchange relationships constitute strategy-practitioner’s emerging dual-identity, which in turn reinforces the practices, generating a self-reinforcing cycle of practice enhancement. Within this cyclic relationship, an inimitable enactment of a strategic practice can be a key source of competitive advantage for informally organized small retail retailers over large FORs. By linking two unconnected prominent approaches to understanding patterns of workplace interactions, namely SAP and SET, the study opens theoretical avenues for exploring strategizing of informal businesses.