This research examines the adoption of Use Case Narratives within the Unified Modeling Language (UML).Using the Technology Acceptance Model (TAM) as a framework, practitioners with UML experience were asked questions to measure their Perceived Ease of Use and Perceived Usefulness of Use Case Narratives and their Intentions to Adopt them. We extend Perceived Usefulness in the context of UML adoption to address the question “usefulness for what purpose(s)?” Generally, we find that TAM explains Use Case Narrative acceptance. More importantly, we find that Perceived Usefulness is explained by usefulness for specific software development tasks. This research provides three main contributions, beginning with an improved understanding of the role of Use Case Narratives in UML projects. Second, the study extends TAM by explaining how a technology is used rather than simply whether it is used. Third, this study provides a framework for future studies into other UML diagrams.