While compassion is generally agreed to be one of the professional qualities required of physician assistants (PAs), the concept has been remarkably difficult to define and measure. The authors describe a series of studies that generated preliminary information about the compassionate qualities of PAs. In an initial survey, PAs rated their own compassionate qualities, after which their patients assessed the same qualities in them. The patients validated three elements of compassion having to do with communication between PA and patient but failed to validate seven other items. Subsequent research dealt with a halo effect related to the wording of the questions and a confounding effect associated with the intimacy of the medical setting.