Although the incidence and composition of HECs has been well characterized, little is known about how HECs assess their performance. In order to describe the incidence of HEC self-evaluation, the methods HECs use to evaluate their performance, and the characteristics of HECs that influence self-evaluation, we surveyed the readers of Hospital Ethics. 290 HECs in 45 U.S. states, the District of Columbia, Puerto Rico and three Canadian provinces, completed questionnaires. Of the 241 HECs included in the data analysis, 97.9% had performed some self-evaluation. Responding committees largely made formative rather than summative evaluations and appeared to evaluate performance in light of their own objectives rather than basing assessments on specific structural, process, and outcome measures of quality. Responding committees used certain evaluation criteria more extensively than others--among these, the number of participants and staff knowledge of the service provided--with the choice of criteria differing with the function being evaluated. Eight characteristics of HECs influenced the probability of self-evaluation, including age, number of beds and meetings, the existence of a mission statement, and a budget. The presence of certain characteristics made HECs six times more likely to evaluate their performance than HECs without the characteristic.