Studies of glottal stop realization have shown that it is often not produced with full closure (Ladefoged and Maddieson, 1996), but conditioning factors are not well understood. This study focuses on Hawaiian, which has phonemic glottal stop that is contrastive in both word-initial (/ˀaka/ “laugh,” [aka] “shadow”) and word-medial position (/pua/ “flower,” /puˀa/ “to excrete”). Glottal stop realization is examined with respect to word position, different versus identical flanking vowel (/puˀu/ “hill”), and duration of the target /VˀV/ sequence. Data from eight native speakers come from the Ka Leo HawaiÊ»i radio program. The majority of glottal stops are produced as a period of creaky voice (63%), either in a modal-creaky-modal, modal-creaky or creaky-modal configuration. Full closures (6.6%) were more likely in word-initial position, and identical flanking vowels led to longer periods of creak. Some tokens had only an intensity dip. Shorter target intervals had longer proportions of creak. These findings for the glottal stop phoneme are consistent with research on the timing of contrastive voice quality in vowels, which show a preference for modal-nonmodal-modal patterns to ensure that vowel quality, voice quality, and tone are recoverable (Silverman, 1997). Effects of word position and flanking vowel are also related to recoverability and segmentation.