Engineering judgment has always played a predominant role in geotechnical design and construction. Until earlier this century, most of this judgment was based on experience and precedents. The role of  judgment in geotechnical practice has undergone significant changes since World War II as a result of theoretical, experimental, and field developments in soil mechanics, and more recently, in reliability theory. A clarification of this latter change particularly is needed to avoid misunderstanding and misuse of the new reliability-based design (RBD) codes. This paper first provides a historical perspective of the traditional factor of safety approach. The fundamental importance of limit state design to RBD then is emphasized. Finally,  an overview of RBD is presented, and the proper application of this new design approach is discussed, with an example given of the ultimate limit state design of drilled shafts under undrained uplift loading. Judgment issues from traditional approaches through RBD are interwoven where appropriate.