The purpose of this study is to determine the impact of gender and hormones (estradiol, progesterone, testosterone and cortisol) on responses to stress and smoking cues presented in daily, "real-world" cue presentations compared to a final cue session in a lab. In addition, the study will examine the impact of a single dose of oxytocin (chemical produced in the body) versus placebo (inactive substance) on stress in males and females.