Much of previous research in the evaluation of awareness systems has focused primarily on systems for synchronous collaborations among individuals working on a shared task, and on awareness systems that do not sufficiently take account of the situated and socially mediated nature of work practices.This work demonstrates the need for a PCA evaluation method for decision support systems that support awareness of activity at the work practice level and enable collaboration and decision support among individuals working on separate tasks across geographical and organizational boundaries. A key strength of the evaluation procedure reported in this work lies in the use of multiple methods that combine quantitative, qualitative and the situation awareness evaluation method of SAGAT in order to highlight deeper issues of perceived usefulness and perceived ease as well as their impact on user acceptance. CaDHealth prototype was evaluated using two key tasks: a cross-boundary awareness task and a decision support task. User-centered evaluation reveals that the incorporation of PCA into the design of telehealth systems for cross-boundary decision support enhances system usefulness, acceptability and user adoption. The use of qualitative methods reveal that making sense of other people’s activities and decision making patterns at the work practice level and across boundaries requires gaining awareness of their activities at three levels of practice, which we refer to as ontological awareness, stereotyped awareness and situated awareness. The results are line with the central goal of usability testing (Dumas and Reddish, 1999), and previous studies (e.g. Davis, 1989), which observed that perceived usefulness is a strong correlate of user acceptance.