Synthesizing knowledge from psychology and marketing research, an understanding of nonverbal communication can help address when and how customers express their underlying feelings in retail interactions that are not evident in direct verbal expressions. Examining nonverbal behavior as an indirect measure of consumer response can enable retailers to better understand the needs of their customers. Nonverbal communication theory is used to develop a conceptual framework that builds on prior research on the situation, expressivity, social status, display rules, and their effects on customer expression. Lay wisdom suggests that customer expression should be revealing (e.g., "the eyes are the windows to the soul"). However, research reveals a myriad of situational factors that may lead customers to mask their true feelings. This paper offers nine theoretical propositions and summarizes research evidence related to these pro-positions from various substantive domains for marketing research.