This chapter provides a synthesis of the complex range of current practices in measuring fluency, from temporal features of speech such as speech rate and frequency of pauses, to prosodic features of speech such as intonation and stress patterns, and sociolinguistic features of turn taking and degree of dominance in a conversation, and highlights the complexities involved in measuring L2 fluency. After providing a historical perspective to the measurement of fluency, we will present a summary of the most frequently used fluency features in SLA studies, and conclude by offering a list of measures that have been suggested as more reliable representatives of utterance fluency.