We report on the smoking patterns and characteristics of individuals who smoke at night. We also explore the relationship between night smoking, nicotine dependence, and cessation outcomes. Participants (N = 691) were heavy smokers enrolled in cessation research clinics. Data were from three studies. Using ecological momentary assessment, participants monitored their smoking (ad libitum, day and night) on electronic diaries (EDs) during a 2-week baseline period and for 4 weeks following a target quit day. A total of 41% of smokers recorded at least one episode of night smoking. Within this group, night smoking occurred on 26% of nights, averaging two episodes per night. ED data correlated with a single self-report item assessing the frequency of night smoking. Night smoking was associated with greater nicotine dependence and daily caffeine consumption. It also predicted risk for lapsing beyond traditional measures of nicotine dependence. Night smoking is common, is associated with nicotine dependence, and it represents additional risk for cessation failure. People who smoke at night may need nicotine replacement therapy overnight. Future research should determine whether treatments that improve sleep quality also improve cessation outcomes in night smokers.