The aim of our research is to create a system whereby human members of a team can collaborate in a natural way with robots. In this paper we describe a Wizard of Oz (WOZ) study conducted to find the natural speech and gestures people would use when interacting with a mobile robot as a team member. Results of the study show that in the beginning participants used simple speech, but once the users learned that the system understood more complicated speech, they began to use more spatially descriptive language. User responses indicate that gestures aided in spatial communication. The input mode that combined the use of speech and gestures was found to be best. We first discuss previous work and detail how our study contributes to this body of knowledge. Then we describe the design of our WOZ study and discuss the results and issues encountered during the completion of the experiment.