Professional ethics has not been a major focus in industrial-organizational (I-O) psychology—in comparison with our study of unethical behavior in organizations. Consequently, we know very little about ethical situations actually faced by I-O psychologists. This article presents and tests a structural perspective on understanding the nature of ethical dilemmas that can facilitate such study. A taxonomy of five paradigmatic forms of ethical dilemmas is defined and placed in a theoretical context. Narrative descriptions of 292 ethical situations were obtained from a sample of 228 professional members of the Society for Industrial and Organizational Psychology (SIOP) in the United States and were used to empirically test the taxonomy. The narratives were content analyzed for form of dilemma, work domain of occurrence, relevance to human resource administration concerns, and favorability of the situation’s resolution. The work domains that were most problematic were academic research/publication activities, individual assessment/assessment centers, consulting issues regarding the client, and academic supervising/mentoring. There were no significant differences as a function of respondents’ sex, seniority, or professional membership status (member/fellow). This relatively “content free” structural aspect of ethical dilemmas enables comparisons across different domains (of professions, organizations, demographic groups, age cohorts, etc.) in which the overt idiosyncratic ethical problems experienced are not commensurable. Similarly, it can yield interpretable longitudinal comparisons despite changes in the manifestations of ethical problems encountered over time.