This article focuses on why people may become dishonest when they are unfortunate. Studies have shown that dishonesty increases in unfortunate or unfair situations, suggesting that misfortune could be used as a self-serving justification. I investigate this effect by analyzing the effect of luck on participant dishonesty in a laboratory experiment. I also control for participants’ belief about others’ honesty in fortunate and unfortunate situations. Participants were more dishonest when they were unfortunate and expected other participants to be more dishonest in similarly unfortunate situations. The similarity of the effects of fortune on expected and actual behaviors suggests that this norm can facilitate self-serving justification. The frequency of dishonest behavior was associated with higher individuals’ beliefs in others’ dishonesty. This effect was particularly important for participants who believed that others would have been dishonest even in fortunate situations. It therefore appears that the justification depends both on being unfortunate and the fact that some people assume others do not behave honestly even when they are fortunate.