The Levels of Use (LoU) interview has been developed to study implementation as a dynamic process. This paper focuses on the use of a mathematics skills monitoring system and reports how information collected during the typical LoU interview provided the data for assigning each teacher to a configuration or pattern of use of the monitoring system. The monitoring system and the technical procedures for deriving the configurations from the interview data are reported. The primary objective of the paper is to describe in detail the methods used to discover how teachers were using the program and to cluster the teachers into groups with similar patterns of behaviors. The relationships between teacher behaviors and student achievement illustrate one application of the results of these procedures. (Author/MLF)