This book offers science-based recommendations for expert witness practice. There is significant literature on the effects of expert testimony on judge and juror decisions, yet there has been no systematic attempt to formulate strategies from this evidence that experts could adopt to increase the effectiveness of their testimony. Around 86 percent of civil cases involve expert testimony, often with multiple experts in a single trial. Psychologists provide their specialized knowledge to educate courts and juries about psychological science that elucidates trial-relevant issues and to provide assessments of psychological constructs that are relevant in a forensic context in both criminal and civil litigation. Chapters discuss research, with key implications for the presentation of expert testimony in court.