The present article proposes a critical discussion of “demand characteristics”. This notion, despite its longstanding and widespread use in behavioral research, suffers from significant conceptual ambiguities. After briefly discussing the historical roots of “demand characteristics” and stressing that this notion remains highly influential in psychological research (Section 1), we proceed to its conceptual analysis (Section 2). Here, we discuss the complex nature of “demand characteristics” regarding effects, mechanisms, and measures. Then, we propose a Multifaceted Demand Characteristics Model (Section 3), and we apply it to two research domains of high contemporary interest: Evaluative Conditioning (Section 4.1) and Rubber Hand Illusion (Section 4.2). In the General Discussion, we summarize the central insights of the current analysis and discuss when and how theorization around “demand characteristics” may prevent and help advance behavioral research and interventions.