This text is based on the Texas Instruments short course on Mechanical Tolerancing for Six Sigma. It includes all phases of dimensional management, and developments that have been made at Texas Instruments in the areas of concurrent engineering, six sigma, statistical tolerancing, performance sigma and defect prediction for pieceparts and assemblies. It also includes practical approaches to dimensioning and tolerancing, tradeoffs between design and manufacturing, practical ways to inspect tolerances, new developments in the "paperless" environment, approaches used in tolerancing software and design by assembly. This approach ties the design community and the manufacturing community together to produce optimum designs and pieceparts. Included are several real-world examples.