This study is based upon two ski seasons worth of data from fifteen ski areas in the United States. A total of 21 817 downhill (DH) injuries and 1194 snowboard (SB) injuries occurred during 8.20 million skier visits. The injury data came from Ski Patrol reports. Control groups of 2318 DH and 255 SB skiers were used to estimate demographic characteristics of the populations at risk. The study looks at the differences between DH skiing and SB skiing; differences between control and injured groups of skiers for both activities (DH and SB skiing); differences between male and female skiers; differences due to ability level; the relationship between lessons and injuries; and the biomechanics of snowboard injuries.