Adherence to positive airway pressure (PAP) therapies is poor, particularly among low-income populations and racial minorities. This study tested a low-resource, brief telephonic health coaching intervention to improve PAP adherence. Post hoc analysis of a quality improvement initiative in which English- and Spanish-speaking patients from a county-based public health system were randomly assigned to receive health coaching or usual care. An unlicensed, trained health coach called patients three times to resolve barriers to adherence. A per-protocol analysis was conducted for adherence measures collected by device modem at baseline and 30 days. Of 131 people for whom device data were available, 56 were randomized to health coaching and 75 to usual care. At baseline, 47.3% of patients had used their device at any time in the past 30 days, with a mean of 2 hours of use per night. At 30 days, adjusting for baseline, patients in the coaching arm were more likely than usual care patients to use their device (55.4% vs. 41.3%, p = 0.03), and they increased their use for 0.4 hours over usual care (p = 0.04). This pilot study suggests that a low-cost intervention could be effective at improving PAP adherence, even in a population known to have poor adherence and among long-term PAP users with poor adherence. Future research may examine whether a higher-touch intervention or one using videoconferencing yields greater improvements. This promising intervention warrants further study.