Unlike read or laboratory speech, spontaneous speech contains high rates of disfluencies (e.g. repetitions, repairs, filled pauses, false starts). This paper aims to promote ‘disfluency awareness’ especially in the field of phonetics –which has much to offer in the way of increasing our understanding of these phenomena. Two broad claims are made, based on analyses of disfluencies in different corpora of spontaneous American English speech. First, an Ecology Claim suggests that disfluencies are related to aspects of the speaking environments in which they arise. The claim is supported by evidence from task effects, location analyses, speaker effects and sociolinguistic effects. Second, an Acoustics Claim argues that disfluency has consequences for phonetic and prosodic aspects of speech that are not represented in the speech patterns of laboratory speech. Such effects include modifications in segment durations, intonation, voice quality, vowel quality and coarticulation patterns. The ecological and acoustic evidence provide insights about human language production in real-world contexts. Such evidence can also guide methods for the processing of spontaneous speech in automatic speech recognition applications.