My presentation will introduce results from ongoing research with a user-centered digital library design project, the Digital Water Education Library, that suggest that such communication is not always so straightforward. At the beginning of the project, DWEL's developers and user-developers embraced significantly different understandings of digital libraries, differences that were tacit and ontological in nature. At the same time, DWEL's developers and users did not realise that they were embracing these differences, and assumed that they were in agreement. My presentation will describe how the differences between developers and user-developers were identified, how these differences were subsequently addressed, and the positive effect that these changes had upon the project.