The author presents a series of 30 questions to be used during the voir dire of expert witnesses. The order and format of the questions should be tailored to each case. Questions go beyond the expert’s resume to focus on the expert’s credentials, competency, knowledge of the subject matter, and relevance to the case. Specific questions focus on the duties and functions of their current position, the subject matter of specialty, length of time at current position, and membership in professional organizations. The article reviews the basis and functions of expert witnesses and describes the five main types of expert witness: (1) lay people; (2) technician/examiner; (3) practitioner; (4) specialist; and (5) scientist. The “Daubert Trilogy” is reviewed, which consists of three cases that established the standard of review and criteria for expert witness testimony. According to the Daubert standards, scientific testimony must be both reliable and relevant to the case. The reliability requirements of scientific evidence are presented, followed by a discussion of the qualifications and competency requirements for expert witnesses, who may be qualified through knowledge, skill, practical experience, training, education, or a combination of these factors. After the establishment of competency, an expert witnesses’ knowledge of the subject matter will affect the weight and credibility of their testimony. A textbox within the article presents a simplified restatement of Federal rules affecting expert testimony. Figures, references