This paper argues that current HIV/AIDS intervention models in southern India--in particular, those targeting the prevention of parent-to-child transmission (PPTCT)--underutilize the private sector and thereby compromise an efficient integration of HIV/AIDS humanitarian responses into India's health development system. While PPTCT is a critical strategy for curbing the HIV/AIDS epidemic-particularly in countries like India, where prevalence rates among young women are escalating-the cascade of prepartum, intrapartum, and postpartum PPTCT interventions are often difficult for women and spouses to access as a result of socio-cultural, structural and economic obstacles. Recognizing the complex ecologies within which PPTCT interventions must take place, qualitative analysis focussed on current PPTCT gaps in southern India and how healthcare providers and policymakers are moving to scale-up PPTCT by integrating into maternal, child and reproductive health services. Fieldwork highlighted a particularly stark gap in PPTCT delivery-the divide in scale-up efforts between public facilities and the private sector, which provides over 50% of national antenatal services. The private sector often serves as women's first point of healthcare contact, as they will avoid reputably poor-quality public facilities; vulnerable groups (e.g. rural and urban poor, tribal communities) are also seeking out subsidized private care, notably in faith-based facilities. Recognizing the need to revise the current humanitarian and health response, this paper details initial efforts to integrate into private care, with aim to present practitioners' successes, challenges and good practices for use in cross learning and a foundation for future research. This paper's analysis makes recommendations for key PPTCT providers and emphasizes the need to: (a) saturate PPTCT services in the private sector, and (b) strengthen mechanisms for integrating PPTCT across sector (private, public, and civil society) and decentralizing deeper into rural India to access vulnerable women, infants and spouses.