The goal of thls work is the enrichment of human-machlne mteractIons in a natural language envlronment. 1We want to provide a framework less restrictive than earlier ones by allowing a speaker leeway tn forming an utterance about a task and in determining the conversational vehicle to deliver it, A speaker and listener cannot be assured to have the same beliefs, contexts, backgrounds or goals at each point in a conversation.As a result, dlfflcultles and mistakes arise when a listener interprets a speakers utterance.These mistakes can lead to various kinds of mlsunderstandlngs between speaker and hstener.including reference failures or failure to understand the speaker's mtentlon.We call these mtsunderstandlngs mlscommunmatlon Such m~stakes constitute a klnd of "ill-formed" input that can slow down end possibly break down communication.Our goal ~s to recognize and Isolate such mlscommunlcattons and circumvent them.Thls paper will hlghhght a particular class of mlscommunlcatlon -reference problems -by descrlbmg a case study, includlng techniques for avoldlng failures of reference [J starts to install the BASEVALVE.backs off, looks at it again and then goes ahead and installs it] J. 8 Okay A: 9 Now screw that blue cap onto I0. the bottom of the maln tube.[J screws TUBEBASE onto MAINTUBE] J. 11.Okay A. 12 Now.there's a--13.a red plastic piece [J starts for NOZZLE]14 that has four gizmos on It.