Yosemite Decimal System

The Yosemite Decimal System (YDS) is a rating system used by rock climbers to choose appropriate climbs that are challenging, within their abilities, and to bring proper gear. There are many factors which influence the ratings, such as the difficulty, time commitment, length of climb, and risk. Although YDS is mostly used in the United States, YDS classes are mapped to other national and regional climbing rating systems.

YDS was leveraged to chart existing LCSH terms to the different YDS classes.

YDS ClassDefinition from Appendix A in Mountaineering: The Freedom of the HillsLibrary of Congress Subject Headings KeywordsTitle or Description
Class 1Hiking.Hiking-Hiking or hiker
Class 2*Simple scrambling, with possible occasional use of the hands.HikingScramblingScrambling
Class 3*Scrambling; hands are used for balance, a rope might be carried.Rock climbingScramblingScrambling
Class 4Simple climbing, often with exposure. A rope is often used. A fall could be fatal. Typically natural protection can be easily found.Rock ClimbingScramblingScrambling
Class 5Where rock climbing begins in earnest. Climbing involves the use of a rope, belaying, and protection (natural or artificial) to protect the leader from a long fall.Rock climbing-Rock climbing or rock climbers
5.0-5.7Easy for experienced climbers; where most novices begin.Rock climbing-Rock climbing
5.8-5.9Where most weekend climbers become comfortable; employs specific skills of rock climbing, such as jamming, liebacks and mantels.Rock climbing-Rock climbing
5.10-5.11A committed recreational climber can reach this levelRock climbing-Rock climbing
5.12-5.15The realm of true experts; demands much training and natural ability, as well as, often repeated working of a route.Rock climbing-Rock climbing

* If LCSH changes “Alpine scrambling” to Scrambling, then “Scrambling” should be added as a Subject Term to these Classes.