Abstract
This article, based on a longitudinal case study, investigates the development, testing, and adoption of innovations in the treatment of HIV/AIDS. Findings indicate that distinguishing between "evidence production" and "adoption" can be difficult because the adoption of innovations is a negotiated outcome and the nature and role of evidence are not given, stable and exogenous to the adoption process. This means that changes to the distribution of discursive legitimacy and credibility in an adopting system can change evidence production and evaluation, and hence patterns of adoption of innovations.