Abstract This study addresses the question of what is the state-of-the-practice of site characterization methods for locating sinkholes or potential sinkholes in the Great Valley Section of eastern Pennsylvania and northern New Jersey. This geographic area has recently experienced the failures of a large office building and a number of residential structures. Sixty engineering firms practicing in this area were asked to respond to a survey concerning the methods currently being employed for locating sinkholes. Twelve firms responded. This paper provides a summary of the 12 methods used to detect voids, the percentage of firms using the different methods and a description of the reliability of each methods. Recommendations concerning site characterization methods for the Great Valley area are also given.