Presently, 38 states, the U.S. government, and the U.S. military enforce the death penalty. During 1997, 74 people were executed in the United States, while over 3200 others awaited capital punishment on death row. An even larger number of cases were tried unsuccessfully. The research tests several hypotheses, underscored by the latest Supreme Court death penalty decision in Buchanan v. Angelone (1998), about the impact of instructions and arguments by counsel on jurors' understanding and use of mitigation evidence. In addition, the research will explore the impact of jury deliberations on the outcome decision. Death qualified community residents and student mock jurors are participating in a capital penalty hearing. Jurors are randomly assigned to treatment conditions. The results will help understand jurors' understanding of mitigating and aggravating circumstances. %%% Presently, 38 states, the U.S. government, and the U.S. military enforce the death penalty. During 1997, 74 people were executed in the United States, while over 3200 others awaited capital punishment on death row. An even larger number of cases were tried unsuccessfully. The research tests several hypotheses, underscored by the latest Supreme Court death penalty decision in Buchanan v. Angelone (1998), about the impact of instructions and arguments by counsel on jurors' understanding and use of mitigation evidence. In addition, the research will explore the impact of jury deliberations on the outcome decision. Death qualified community residents and student mock jurors are participating in a capital penalty hearing. Jurors are randomly assigned to treatment conditions. The results will help understand jurors' understanding of mitigating and aggravating circumstances.