Ss viewed a pleasant videotape either: (a) alone, (b) alone but with the belief that a friend nearby was otherwise engaged, (c) alone but with the belief that a friend was viewing the same videotape in another room, or (d) when a friend was present. S's smiling, as estimated by facial electromyography, varied monotonically with the sociality of viewing but not with reported emotion. The findings confirm audience effects for human smiles, demonstrate that the effects do not depend upon the presence of the interactant, and indicate that the smiles are better predicted by social context than by emotion. Both naive and expert independent raters given descriptions of the study made predictions that conformed to previous emotion-based accounts of faces but departed from the findings. The results suggest that some solitary faces may be implicitly social, a view consistent with both contemporary ethology, and role and impression-management theories of behavior. © 1991 American Psychological Association.