The use of consultants in providing preconstruction engineering design services for state departments of transportation has increased over the last 20 years. This has resulted in several investigations into the cost-effectiveness of this trend. This paper reviews past studies, examines their methodology, suggests improvements to certain parts of the commonly used investigative process, and demonstrates their use in an application to the Louisiana Department of Transportation and Development. The suggested improvements include using the same project to compare in-house and consultant design costs (instead of the use of similar projects, as in most studies), performing a detailed analysis of overhead rates that are comparable between state and consultants, and measuring comparative design costs as the ratio of in-house to consultant design costs instead of as the ratio of design to construction cost commonly used in past studies. Most previous studies have concluded that consultant design costs are higher than in-house costs or that there is not a significant difference in cost between the two. The Louisiana study found that consultants are approximately 20 percent more expensive than in-house staff in producing road and bridge designs but that the difference was almost entirely due to the extra cost of contract preparation and in-house supervision required for consultant designs. The study also identified factors other than cost that are used in decision making to employ consultants.