Did you ever take something in a supermarket without paying for it? Did you ever keep quiet when receiving too much change at the checkout? Did you ever purchase an item, used it, and returned it to the store afterwards for a refund? Did you ever copy a CD (music/video) from a friend? These and many more are all widespread everyday deceptions by which we -consumers- benefit at the expense of the seller... The general purpose of the present dissertation was to contribute to a more thorough understanding of the why of consumer ethics, allowing marketers to predict unethical consumer behavior, and ultimately prevent consumers from taking advantage of the seller. More specifically, the impact of 1/ individual characteristics (personal values), 2/ situational circumstances (relationship marketing), and 3/ emotional experiences (guilt) within the ethical decision-making processes of consumers are investigated.