The concept of shyness and its measurement were investigated in a series of studies (total N = 1,687). Data collection and analysis proceeded in three phases: the revision and continued development of a measure of shyness, the Social Reticence Scale; a psychometric comparison among five measures of shyness; and an examination of the factor structure underlying the construct of shyness. Phase 1 assessed the reliability and validity of the Social Reticence Scale, including ratings of videotaped monologues and ratings by significant others. Phase 2 compared the five shyness measures with one another on indices of internal consistency and with other relevant measures of emotionality, personality, relationships, and behavior. Items from the five shyness measures were combined in a factor analysis in Phase 3, and the resulting factors were correlated with the self-report and rating data obtained in Phase 2. Overall, the results from these studies confirmed that the shyness measures were valid, reliable, and empirically distinct from measures of related constructs. Behavioral validity was observed for several of the shyness scales. Additional analyses suggested that three interpretable factors underlie responses to the shyness scales but provided little support for drawing conceptual distinctions among types of shyness. Discussion focuses on the implications of these data for the measurement and conceptualization of shyness.