This article describes the development of a dynamic culturally constructed clinical practice model for HIV/STI prevention, the Narrative Intervention Model (NIM), and illustrates its application in practice, within the context of a 6-year transdisciplinary research program in Mumbai, India. Theory and research from anthropology, psychology, and public health, and mixed-method ethnographic research with practitioners, patients, and community members, contributed to the articulation of the NIM for HIV/STI risk reduction and prevention among married men living in low-income communities. The NIM involves a process of negotiation of patient narratives regarding their sexual health problems and related risk factors to facilitate risk reduction. The goal of the NIM is to facilitate cognitive-behavioral change through a three-stage process of co-construction (eliciting patient narrative), deconstruction (articulating discrepancies between current and desired narrative), and reconstruction (proposing alternative narratives that facilitate risk reduction). The NIM process extends the traditional clinical approach through the integration of biological, psychological, interpersonal, and cultural factors as depicted in the patient narrative. Our work demonstrates the use of a recursive integration of research and practice to address limitations of current evidence-based intervention approaches that fail to address the diversity of cultural constructions across populations and contexts.