Sensitive drawings are a distinctive genre of explicit sexual imagery which has become a standard way of illustrating sexual acts in human sexuality textbooks. This essay presents an analysis of signs defining age, ethnic status, class, and sexual identity encoded in such sensitive drawings as used in 23 recent textbooks and of the biases which this encoding reflects. The strong class and heterosexual biases characterizing the images are consistent with those found in the sex manuals which inspired the style of drawing. Functions of the drawings and their relationship to the texts' written materials are discussed, and it is argued that the biases mirror problems in treatment of social class and sexuality and in the treatment of sexual acts, e.g., masturbation, oral sex, and sex, and coitus, as they relate to sexual identities.