People typically attribute lower health risks to themselves than to others, a phenomenon referred to as unrealistic optimism. The present study tested the person positivity bias as a previously unexamined explanation of the phenomenon and analyzed the relationship between unrealistic optimism and expectations of control. High-school students estimated their own and one of three other persons’(the average student's, a randomly chosen student's, or their best same-sex friend's) chances of getting health problems. They also filled out questionnaires measuring locus of control and health-protective behavior. In contrast with the person positivity explanation, unrealistic optimism was not restricted to the “average other” condition. However, unrealistic optimism was stronger in subjects with a more internal locus of control than in subjects with a rather external locus of control. An unpredicted effect of estimation order was observed: Unrealistic optimism was stronger in subjects who estimated the comparison person's risks first than in subjects who started with own risks. This effect can be understood in terms of Codol's observation that people perceive others as more similar to themselves than they themselves are to others.