In May 2003, the Gallup Organization interviewed 1,005 adults (18 years old and older) by phone. Respondents were asked whether they favored capital punishment or life imprisonment without the possibility of parole for murderers. Respondents without an opinion were deleted from the study. Fifty-four percent of the respondents favored the use of the death penalty for murderers. Respondents were also asked, "How often do you think that a person has been executed under the death penalty who was, in fact, innocent of the crime he or she was charged with -- do you think this has happened in the past 5 years, or not?" Seventy-four percent of the respondents reported that they believed that an innocent person had been executed within the last 5 years. Another question asked, "Generally speaking, do you believe the death penalty is applied fairly or unfairly in this country today?" Thirty-six percent of the respondents believed the death penalty was applied unfairly. Independent variables were race, income, urban location, southerner, fundamentalist, Catholic, church attendance, religiosity, confidence in government officials, political orientation, gender, age, and education. The belief that an innocent person had been executed in the last 5 years was associated with lower levels of support for capital punishment, especially among those who believed it was applied unfairly. This link was more likely to be found among African-American respondents than White respondents. Thus, these findings suggest that the prospect that innocent persons will be executed significantly undermines public support for capital punishment. 4 tables and 76 references