I study the collateral signals people produce in talking on the fly. These are signals beyond the conventional words uttered, and include such phenomena as discourse markers (words like well, I mean, and you know), fillers (um and uh), repetitions and repairs (such as "she says well that's- we have to pay our- pay our own"), and prosodic information (such as the pauses between words, prolongation of words, and the melodic pattern of an utterance). One reason these phenomena have not received the attention they deserve is because we are taught to regard them as incorrect, flawed, or inelegant speech, leading us to believe they should be avoided or ignored. Another reason they have been overlooked in the research literature is because they are found primarily in spontaneous natural dialogue, and most speech studied in research laboratories is prepared in advance and rehearsed. My theoretical and empirical work demonstrates that these phenomena are not only worthy of notice, they are of vital importance to successful communication in everyday conversation.