This study tests two explanations of observer accuracy and bias in estimating dating interest and physical attraction. Grammer et al. (1997; 2000) suggest that women are more difficult to accurately read than men, but women should become increasingly transparent as certainty of men’s dating interest increases. The traditional sexual script (TSS) suggests men are perceived to be more interested in and pursuant of sex than women (Gagnon, 1990). Observers will perceive women as having less physical attraction and more romantic interest than men. Heterosexual target participants (N = 98) engaged in 10-12 minute cross-sex interactions, which were video recorded. Third-party observer participants (N = 201) watched 10 clips of interactions, and estimated target attraction and interest. Data were analyzed using MLM (N = 1,858). Results indicate that when physically attracted to or interested in dating, men were more readable than women. There was no support for Grammer et al.’s mechanism. The lowest observer accuracy occurred when women targets were interested in dating and believed their conversational partners were interested in dating too. Results supported TSS in that observer accuracy decreased with increasing female target interest and attraction, and decreasing male attraction. Accuracy suffered because observers overestimated men’s and underestimates women’s attraction and interest. Important findings include: 1) Accurately decoding attraction and interest is difficult. On average, observers were off by 1.8 points on a 7-point scale; 2) A lack of interest and attraction is easier to decode than interest and attraction, particularly in women targets.