The essence of harmful addictive products is that current consumption decreases your future well being but at the same time increases your future desire for those products. In this paper, we explore the implications of self-control problems -- the time-inconsistent taste for immediate gratification -- for the consumption of harmful addictive products. We examine the behavior of both sophisticates -- people aware of their self-control problems -- and naifs -- people unaware of their self-control problems. Self-control problems make you prone to over-consume addictive products, and in all environments naifs do so. In stationary environments, where the temptation to consume may depend on past consumption of the product but not directly on the date, sophistication about the self-control problem exacerbates the tendency to get addicted. But in more realistic environments where the temptation to consume varies day to day or over the course of a lifetime, sophistication can make addiction less likely. We also consider the implications of two models that allow the taste for immediate gratification itself to vary over time. Finally, in part to emphasize the severe consequences for welfare analysis of completely ignoring self-control problems, we illustrate how the “incremental” nature of addictive activities can lead a person with relatively mild self-control problems to hurt herself severely.