Habits are an efficient, often effective means of guiding behavior. This talk will focus on the unique psychological systems involved in habitual behavior. A distinctive feature of habits is that they involve minimal thought. About half of everyday behaviors are habitual; for these behaviors, people often are unaware of what they are doing. Another feature of habits is that, when people don't reason about action, their intentions become inconsistent. Thus, they may not like what they are doing, but they do it anyway. Also, habits are uniquely vulnerable to changes in contexts. When contexts shift, habits are disrupted. Thus, by changing contexts, people may gain control over their behavior and act in line with their intentions.