Planning support systems are geo-information-based tools to support those involved in planning tasks. Many see planning support systems capable of improving the handling of knowledge and information in planning processes. Better handling of knowledge and information could help those involved in planning to handle the ever-increasing complexity of planning tasks. In spite of these potential benefits, planning support systems have not yet become widely used in planning practice. A major problem contributing to the arrear in planning support systems use is the profound miscommunication that exists between planners, planning support systems developers, and researchers. Currently there exists little insight in how to solve this problem and enhance the use of planning support systems. This chapter provides practiceoriented lessons about PSS use. Those willing to apply planning support systems in planning practice may use these lessons to enhance the successful use of planning support systems and the handling of knowledge and information in planning.