We introduce a new usability walkthrough method called Collaborative Critique (CC), which is inspired by the humancomputer collaboration paradigm of system-user interaction. This method applies a "collaboration lens" to assessing the system's behavior and its impact on the user's efforts in the context of the task being performed. We present findings from a laboratory evaluation of the CC method with usability practitioners, in which the results of the CC walkthrough were compared to a benchmark set of problems collected via user testing with two experimental Enterprise Resource Planning (ERP) system tasks.The development of this new usability evaluation method was driven by the need for an approach that assesses the adequacy of the system's support for reducing the user's cognitive and physical effort in the context of the interaction.