Horse and buggy transportation is spreading as rapidly as its Amish and Old Order Mennonite users are, as are buggy crashes with motor vehicles. This study examines the primary causes of 76 reported horse and buggy crashes in Pennsylvania in 2006. The main crash types identified include a motorist rear-ending a forward-moving buggy, motorist failing to pass a buggy, buggy struck while crossing an intersection, and buggy struck while making a left turn. While causative factors varied for each crash type, major factors include the motorist or buggy driver incorrectly comprehending speed differentials, the motorist acting carelessly around the buggy, and miscommunication between the motorist and buggy driver. Within these crash types, buggy conspicuity was neither a major issue nor a possible cause in most.