In a Flexible Manufacturing System (FMS) an Automated Guided Vehicle System (AGVS) is commonly used to move jobs between work-centers. The operation of the AGVS is governed by two categories of AGV dispatching rules: Work center Initiated (WI) Rules, and Vehicle Initiated (VI) Rules. At work centers, jobs are prioritized for processing by Job Dispatching (JD) Rules. This study characterizes system behavior when dispatching rules from each of the three categories are used concurrently and explores the possibility of interaction between rules from different categories. Performance measures specifically directed at AGVS effectiveness such as queue lengths for AGVs and empty AGV travel are used for comparison. Combinations of rules from the three categories are studied under conditions of high and low AGV utilization in a SLAM II simulation model of a hypothetical FMS.