Recently revived interest in the role of birth order in the development of personality has resulted in research investigating the relationship between birth order and the five-factor model (FFM) of personality. One particularly intriguing finding is that firstborns are expected to be higher in conscientiousness. Taking this result and its theoretical rationale from developmental and evolutionary psychology and combining it with growing speculation among human resource management scholars that conscientiousness is a measure of integrity, we would expect to find that firstborns are less likely to engage in unethical behavior. Theory would also suggest that when firstborns do engage in unethical behavior, it would most likely be for personal benefit, while laterborns would be more likely to engage in unethical behavior for the benefit of a group with whom they identify. Additionally, it was hypothesized that men would be more likely than women to engage in unethical behavior. Results show that, contrary to expectations, firstborns are actually more likely to engage in unethical behavior regardless of whom the action benefits. As expected, men reported being more likely to engage in unethical behavior. The findings here failed to confirm previous findings that firstborns are significantly higher in conscientiousness than laterborns. In fact, there were no significant differences according to either birth order or sex, but some personality traits---namely conscientiousness, agreeableness, and openness---were found to correlate negatively with the likelihood of engaging in unethical behavior. Results suggest that differences in the way boys and girls, firstborns and laterborns develop could lend insights into how ethical orientations are formed, but differences in ethical orientation do not appear to be the result of differences in personality.