Peer reporting is a specific form of whistleblowing in which an individual discloses the unethical behavior of wrongdoing by a peer. This study examined peer reporting from the possible moderating aspect, and demonstrated a significant moderating impact on the causal relationships of ethical decision-making process. The findings of this investigation suggest that the intentions involved in reporting peer wrongdoing differs among individuals, and are influenced directly by ethical judgments, attitudes, and subjective norms, while also being influenced indirectly by idealism, relativism, and subjective norms. Besides, compared with externals under high peer pressures, internals under low peer pressures display a stronger relationship between ethical judgment and peer reporting intentions, and between the subjective norm and peer reporting intentions. Last, the relationship between attitudes and peer reporting intentions is similar for both internals under low peer pressures and externals under high peer pressures. Implications of this situation are discussed.