AbstractHow easy is it for individuals to detect low to moderate levels of problem gambling tendencies in others? Are individuals who have problem gambling tendencies themselves, or are close relationship partners, more accurate judges? We examine these questions in two studies involving a total of 336 interacting dyads drawn largely from a university student population. In Study 1 all pairs were strangers, whereas in Study 2 approximately half of the pairs were close. After the “judge” observed the “target” complete a gambling task, the dyad had a face‐to‐face discussion, with topics including favorite pastimes and personal weaknesses. Judges estimated the target's problem gambling tendencies, and both judges and targets self‐reported their own gambling tendencies. There was evidence of modest, albeit somewhat inconsistent, accuracy in individuals’ judgments of the other person's problem gambling tendencies, but no “it takes one to know one” or acquaintanceship effects were apparent. Results also indicated that judges evidenced a projection bias, whereby they saw the target as similar to themselves, especially within close pairs. These results reveal that even after minimal interaction with a stranger individuals can be able to judge the person's gambling tendencies with some accuracy. At the same time, our findings indicating that close others and those with problem gambling tendencies themselves are not more or less tuned in to the early signs of a problem than anyone else suggest that it would be inappropriate to be especially convinced by—or skeptical of—these individuals’ judgments.