Background: Quitlines offer evidence-based, multisession coaching support for smoking cessation in the 50 U.S. states, Canada, and several other countries. Smokers who enroll in quitline services have, "ipso facto," shown readiness to attempt to quit, but noncompletion of coaching services appears widespread and has not been widely investigated. The current study explored the magnitude and correlates of quitline service abandonment. Method: A state's quitline intake, coaching, and nicotine patch/gum utilization data were obtained for smokers who enrolled during the period July 2007 to June 2008 (n = 20,882). Analyses examined demographic, socioeconomic status, nicotine dependence-related, and nicotine replacement therapy-utilization factors associated with completion of only one coaching session (of five offered). Results: Almost half of enrollees (47.8%) completed only one session. All significant predictors together explained less than 4% of variance; not being sent nicotine replacement therapy was most strongly correlated with completion of only one session. A framework is proposed for directing research toward reducing quitline service nonadherence. Conclusions: Premature user abandonment of coaching calls is widespread within a quitline. Further research should determine the extent of the problem in national quitline systems, increase knowledge of mediators of nonadherence, and develop strategies for increasing coaching completion. (Contains 3 tables.)